As I told some of you, I'm away in New York right now. Naturally, since I'm out of town, that = computer problems.
I narrowed it down to my Linksys WRT54g router dropping most packets for non-established connections (but, strangely, working fine for established connections). That means that once I'm SSHed in, everything's fine.
I wish I could reboot my router remotely, but it appears that Linksys WRT54g with stock firmware doesn't let you. I've been looking for a way, but it doesn't look promising.
So, if you manage to see this before I get back on Sunday, congrats!!