I would also like to suggest the addition of a weekly digest option. I know someone who doesn't seem keen on getting emails every day, but she wouldn't mind something like a weekly digest.
Hmm. I don't know, really. I'd have to ask her. She might be fine with some of the other options (like seeing new threads only), but I thought I'd suggest the weekly digest since I noticed there wasn't one. It's not a huge issue for me personally.