These are the Senators who might be convinced to vote to support the filibuster, and if yours is on the list I strongly recommend that you call and nag them to come down on the side of truth, virtue, and silly but useful political processes. If you think it was funny when a senator could filibuster by reading the phone book, now we have virtual filibusters--the mere threat of a filibuster can have its effect, and no one has to talk or listen for hours and hours.
The filibuster is an emergent property of the US Senate not having rules to limit the amount of time spent on debate, and it's valuable because it keeps majorities from completely over-ruling minorities. The particular issue is federal judges (with the Supreme Court likely to be an issue in the forseeable future), but even if you're fond of the current administration, you should consider the possibility that you might want some limits on any future administration you don't like as much.
Susan Collins (ME) - (202) 224-2523
Mike DeWine (OH) - (202) 224-2315
Judd Gregg (NH) - (202) 224-3324
Chuck Hagel (NE) - (202) 224-4224
Dick Lugar (IN) - (202) 224-4814
Lisa Murkowski (AK) - (202) 224-6665
Pat Roberts (KS) - (202) 224-4774
Gordon Smith (OR) - (202) 224-3753
Arlen Specter (PA) - (202) 224-4254
John Sununu (NH) - (202) 224-2841
John Warner (VA) - (202) 224-2023
ETA: It's been confirmed by a call to her office that Olympia Snowe (ME) - (202) 224-5344 has not confirmed her vote to continue the use of the filibuster. Please consider her to be added to the list of people to call.
I called Arlen Spector, and was only on hold for a few minutes.
Wikipedia--recommended, including a section on an inventive high-tech Canadian filibuster.
List of Senators.
This country's planted thick with laws from coast to coast--man's laws, not God's--and if you cut them down--and you're just the man to do it--d'you think you could stand upright in the winds that would blow then? Yes, I'd give the Devil benefit of law, for my own safety's sake. ---Robert Bolt, _A Man for All Seasons_