These are the big boys, though this list will likely change next year. 2008 is when the real repercussions of the subprime mortgage crisis and resulting financial issues will impact these ratings. Cadwalader, Wickersham & Taft, especially, showed some of the effects, as it was the most exposed. Cadwalader's profits per partner plunged a whopping 6.2% from the previous year.
Three firms hit the over-$2-billion-in-revenue mark for the first time: Latham & Watkins, Skadden, Arps, Slate, Meagher & Flom, and DLA Piper

Debevoise & Plimpton showed particularly strong results, with a 23.5% increase in profits and the second-highest increase in profits per partner.
So if you are looking for a career in Big Law, these are the firms that epitomize the term. Good luck!

The Lawyers Top 50 US Law Firms By Revenue