There aren't too many sites out there devoted to Laura, but there are ways you can find information about her and the work she did previous to joining the cast of ER.

The Unofficial Laura Innes Fan Page
This site has a lot of information, but it doesn't look like it's been updated in a very long time.

The Internet Movie Database
Here's where you can find a complete filmography of Laura's work, both in films and on TV. The IMDB even has records of all the guest starring work Laura did on various shows, and records of the two episodes of ER and the one episode of the West Wing that she directed. (And if you don't know which ER episodes she directed -- shame on you!)

NBC's Official Bio page
This has a brief biography, and a pic of Laura that looks like it was from third season.

TV Now's Listing for Laura
TV Now has a listing containing every TV appearance that Laura will make (on American television). They update their site once a month.

TNT's page with Laura's Bio
The home of ER's syndicated reruns has a brief bio on Laura.

This site is unofficial and is in no way affiliated with Laura Innes, ER, Warner Brothers or NBC.
This site is simply a show of fan appreciation and support.