MoveOn is organizing an electronic petition to Senators asking that they resist the attempt to stampede them into approving a nominee. MoveOn thinks Bush is going to announce his choice after deliberating all the way until next Tuesday. They want to turn in their petition before then.
If you want to show support for the Senate to do a thorough job of advising and consenting (or not consenting) on this important nomination, click and sign MoveOn's online petition.
Democracy for America (Howard Dean's organization which grew out of his Presidential campaign, I think) is also circulating a petition sponsored by Senator Patrick Leahy, ranking Democrat on the Judiciary Committee. That one's at Democracy for America.
And for more links and places to get involved, check out campn's blog.