If you think they have done a good job, you should vote for them again.
If you don't, today is your day to do something about it.
Based on papers by Bafumi et al, Kastellac et al, and Erikson et al, some mild assumptions about turnout, Senate race data from 2000, House races from 2002 and 2004, adjustments for population growth, and individual race polling, I've created a district-by-district tally of the expected total vote for both Senate and House. This is, I think, rather less subject to uncertainty than the actual seat totals, which depend in detail on the precise distribution of votes.
For posterity, my predictions:
28.5 M votes for Democratic Senators
22.5 M votes for Republican Senators
(12 point difference)
(A note on methodology in CT: since Lieberman has publicly campaigned on a promise to caucus as a Democrat, both Lieberman and Lamont are counted as Democrats for this tally. But CT is small and the results do not change noticeably for other ways of counting).
42.0 M votes for Democratic Representatives
35.8 M votes for Republican Representatives
(8 point difference)
Also for posterity: Dems net 25 House seats and four Senators
Update (0205 11/08): With solid data from most districts, I am estimating the aggregated Senate vote is going to be 28.1M for Republicans, 35.7M for Democrats. Percentage wise, this differs by 0.07% from my prediction. Obviously, my absolute turnout level was wrong.