I'd add Rep. John Doolittle (R-CA) as a potential Abramoff casualty, but so far it seems that the case against him hasn't stuck, even more than the others.
And to continue the roll call:
Josh mentions Katherine Harris, but she's really a Duke Cunningham scandal casualty and was unpopular to start with.
And Tom DeLay is his own can of worms. Short of a conviction in Texas, though, I wouldn't count him out.
So what gives? You might attribute it to the "sure, he's dirty, but he's our dirty congressman" mindset. Burns and Ney are accomplished porkers. As for Reed, he's got a core group of supporters who have their fingers in their ears. And the case against him is sufficiently complicated (by his own design), that it's easier to shrug it off. Doolittle is so corrupt that it's hard to find one thing to focus on; you might say it's the same thing with DeLay.
Perhaps it just takes time for things to sink in. And the campaign season hasn't really begun. But it's staggering to think that these politicians have managed to go on this long with their heads in a noose.