This was a very difficult section to compile. It required checking numerous websites and cross-checking them with actual numbers from the series.
Please note though that some power levels are merely estimates as they weren't always provided (especially in DragonBall GT).
I thought long and hard about how to organize this section. I finally decided on organizing it by saga and by going in order of power rather than going in chronological order of character appearances. (Power does give a fairly accurate picture of order of appearance though.)
_________________________________________________
DRAGONBALL
The 21st Tenkachi Budakai:
* Bacteria: 14
* Lanfan: 14
* Guilan: 71
* Yamcha: 73
* Nam: 87
* Krillin: 97
* Goku: 124
* Jackie Chun (Master Roshi): 139
* Tao Pai Pai: 146
* Karin: 146
* Goku after training with Karin: 157
* Son Gohan (a different one): 156
The 22nd Tenkachi Budakai:
* Wolf Man: 19
* Pam Put: 56
* Yamcha: 128
* Chiaotzu: 138
* Choun: 139
* Krillin: 146
* Tambourine: 173
* Cymbal: 173
* Yajirobe: 181
* Tien: 186
* Goku: 186
* Piccolo Daimao old: 201
* Piccolo Daimao young: 260
* Goku after holy water: 265
The 23rd Tenkachi Budakai:
* Chi-Chi: 73
* Yamcha: 167
* Tao Pai Pai: 189
* Krillin: 206
* Tien: 250
* Shen God: 301
* Piccolo: 320
* Goku: 330
________________________________________________
DRAGONBALL Z
Arrival of Raditz:
* Turtle: 0.001
* Farmer with shotgun: 5
* Master Roshi: 139
* Chiaotzu: 145
* Krillin: 206
* Tien: 250
* Piccolo with heavy clothing: 322
* Goku with heavy clothing: 330
* Piccolo without heavy clothing: 500
* Goku without heavy clothing: 600
* Gohan: 710
* Piccolo after first Makansappo: 900
* Goku after Kamehameha: 1,000
* Gohan when he was mad: 1,130
* Raditz: 1,200
* Piccolo after final Makansappo: 1,440
Vegeta and Nappa:
* Chiaotzu: 1,150
* Saibamen: 1,200 each
* Yamcha: 1,250
* Krillin: 1,350
* Tien: 1,600
* Gohan: 1,900
* Krillin after mega energy blast: 2,000
* Piccolo: 2,000
* Tien after mega blast: 2,900
* Gohan after his Mesenko: 3,000
* Gohan healed after battle: 2,800
* Nappa: 4,000
* Goku: 5,000
* Goku powered up: 10,000
* Goku after Kao-ken: 13,000
* Goku healed (long after the fight): 15,000
* Vegeta: 16,000
* Vegeta powered up: 18,000
* Goku after Kao-ken x 2: 16,000
* Goku after Kao-ken x 3: 25,000
* Goku after Kao-ken x 3 + Kamehameha: 40,000
* Goku after Kao-ken x 4 + Kamehameha: 95,000
* Vegeta after Gallet Gun: 35,000
* Gohan transformed into an Oozaru: 40,000
* Vegeta transformed into an Oozaru: 180,000
Frieza Saga:
* Goku in Captain Ginyu's body: 10,000
* Guldo: 10,000
* Krillin: 12,000
* Gohan: 19,000
* Kui: 21,000
* Dodoria: 22,000
* Zarbon: 23,000
* Captain Ginyu in Goku's body: 23,000
* Vegeta (healed after fight with Goku): 27,000
* Krillin after Guru charge-up: 30,000
* Zarbon as a hideous monster: 35,000
* Nail: 42,000
* Vegeta (healed after fight with Zarbon): 45,000
* Gohan after Guru charge-up: 50,000
* Recoome: 60,000
* Burter: 70,000
* Jeice: 75,000
* Jeice after crusher ball attack: 85,000
* Captain Ginyu: 120,000
* Vegeta (healed after fight with Recoome): 130,000
* Goku powered up against Captain Ginyu: 180,000
* Piccolo: 400,000
* Frieza: 530,000
* Frieza's second form: 700,000
* Piccolo merged with Nail with heavy clothing: 800,000
* Goku healed after Ginyu fight: 870,000
* Piccolo merged with Nail without heavy clothing: 880,000
* Vegeta (healed by Dende after Krillin knocks him out): 950,000
* Goku after Kao-ken x 10: 1,150,000
* Goku after Kao-ken x 20+ Kamehameha: 1,425,000
* Frieza's third form: 1,500,000
* Frieza's fourth form: 2,000,000
* Goku after his Spirit Bomb: 2,500,000
* Frieza's robot form: 2,500,000
* Goku as a Super Saiyan: 3,000,000
* Future Trunks: 4,000,000
Cell Saga:
* Hercule/Mr. Satan: 140
* Yamcha: 2,000,000
* King Cold: 3,000,000
* Android 19: 3,000,000
* Android 20: 3,500,000
* Cyborg Frieza: 4,000,000
* Krillin: 4,000,000
* 19 after absorbing Vegeta's Ki: 4,000,000
* Gohan: 4,000,000
* Piccolo: 4,500,000
* Vegeta: 5,000,000
* Trunks 14 yrs. Old: 5,000,000
* Tien: 5,000,000
* 17's future form: 5,250,000
* 18's future form: 5,500,000
* Trunks 17 yrs. Old: 6,000,000
* Goku: 6,000,000
* Cell: 6,000,000
* Android 17: 7,000,000
* Android 18: 7,500,000
* Kamiccolo (fusion of Kami and Piccolo): 7,500,000
* Cell after absorbing humans: 8,000,000
* Android 16: 11,000,000
* Kamiccolo after Spirit and Time training: 15,000,000
* Cell in form 2: 16,000,000
* Vegeta as a Super Saiyan: 17,000,000
* Trunks as a Super Saiyan: 18,000,000
* Trunks after Spirit and Time training: 21,500,000
* Cell in Perfect form: 20,000,000
* Gohan after Spirit and Time training: 20,000,000
* Vegeta after Spirit and Time training: 22,000,000
* Goku after Spirit and Time training: 23,000,000
* Goku as a Super Saiyan: 26,000,000
* Cell in Mega Perfect form: 35,000,000
* Gohan as Super Saiyan 2: 35,000,000
* Gohan after killing Cell with a Kamehameha: 40,000,000
Majin Buu Saga:
* Trunks: 1,500,000
* Goten: 1,500,000
* Gohan: 3,000,000
* Gotenks: 3,000,000
* Vegeta: 5,000,000
* Goku: 5,000,000
* Trunks as a Super Saiyan: 10,000,000
* Goten as a Super Saiyan: 10,000,000
* Vegetto: 10,000,000
* Gotenks as a Super Saiyan: 20,000,000
* Gohan as a Super Saiyan: 25,000,000
* Piccolo: 26,000,000
* Vegeta as a Super Saiyan: 27,000,000
* Goku as a Super Saiyan: 27,000,000
* Fat Buu: 45,000,000
* Gohan as Super Saiyan 2: 48,000,000
* Vegeta as Super Saiyan 2: 49,000,000
* Ultimate Buu: 50,000,000
* Goku as Super Saiyan 2: 50,000,000
* Vegetto as a Super Saiyan: 54,000,000
* Good Buu: 55,000,000
* Gohan with the Z Sword: 55,000,000
* Evil Buu: 65,000,000
* Super Buu: 70,000,000
* Gotenks as Super Saiyan 3: 75,000,000
* Majin Buu: 80,000,000
* Majin Buu as Gotenks: 90,000,000
* Goku as Super Saiyan 3: 80,000,000
* Majin Buu as Vegetto: 100,000,000
* Goku after Mega Spirit Bomb: 100,000,000
* Vegetto as Super Saiyan 2: 100,000,000
________________________________________________
DRAGONBALL GT
Bebi:
* Pilaf: 100
* Chibi Goku: 2,000,000
* Goten: 2,500,000
* Trunks: 2,500,000
* Chibi Goku as a Super Saiyan: 5,000,000
* Gohan: 9,000,000
* Vegeta: 10,000,000
* Goten as a Super Saiyan: 15,000,000
* Trunks as a Super Saiyan: 15,000,000
* Goku: 15,000,000
* Chibi Goku as Super Saiyan 2: 20,000,000
* Gohan as a Super Saiyan: 27,000,000
* Vegeta as a Super Saiyan: 30,000,000
* Chibi Goku as Super Saiyan 3: 45,000,000
* Gohan as Super Saiyan 2: 50,000,000
* Vegeta as Super Saiyan 2: 50,000,000
* Goku transformed into a Golden Oozaru: 50,000,000
* Vegeta transformed into a Bebi-Oozaru: 165,000,000
* Goku as Super Saiyan 4: 170,000,000
Super 17:
* Krillin: 3,000,000
* Nappa: 17,000
* Frieza: 34,000,000
* Cell: 35,000,000
* Pan: 35,000,000
* Android 18: 36,000,000
* Android 17: 39,000,000
* Goten as a Super Saiyan: 63,500,000
* Trunks as a Super Saiyan: 63,800,000
* Gohan as a Super Saiyan: 72,000,000
* Rudou: 73,000,000
* Vegeta as a Super Saiyan: 75,000,000
* Android 17 in Super Form: 175,000,000
* Goku as Super Saiyan 4: 175,000,000
* Goku after his Dragon Punch: 200,000,000
Evil Shenrons:
* Vegeta: 13,000,000
* Goku: 15,000,000
* Vegeta as a Super Saiyan: 30,000,000
* Goku as a Super Saiyan: 35,000,000
* All 7 Evil Shenrons weakened: 50,000,000
* Vegeta as Super Saiyan 2: 50,000,000
* Goku as Super Saiyan 2: 60,000,000
* All 7 Evil Shenrons: 75,000,000
* Vegeta as Super Saiyan 3: 110,000,000
* Goku as Super Saiyan 3: 120,000,000
* Vegeta as Super Saiyan 4: 160,000,000
* Goku as Super Saiyan 4: 180,000,000
* All 7 Evil Shenrons all merged together: 350,000,000
* Gogeta as Super Saiyan 4: 360,000,000
* Goku merged with 7 Shenrons/dragon balls: 1,000,000,000