I have a Treo180 and an AT&T Broadband email account. Unfortunately (or fortunately), AT&T only permits access to this via SSL.

TreoMail Internet edition doesn't do it (or didn't as of beta period). The only one I've found that does support POP3 over SSL is Eudora. But Eudora is the least Treo-friendly app. Also, when composing email, it doesn't auto- capitalize and lower-case properly. Mostly just gets stuck in uppercase mode. Really annoying.

Iambic, Basejet, and SnapperMail don't appear to support SSL. Are there any others that do?

If Iambic, Basejet, or Snapper is listening, I would buy your software if it supported SSL...