POP3 Email Client
You'd think there would be a lot of good POP3 code floating around for .NET since it's a ubiquitous protocol that's been around more than 10 years but the libraries I could find were either commercial, didn't support MIME attachments, or just didn't seem like they were trustworthy code...
As I was about to give up I found Pawel Lesnikowski's Mail namespace for C#, which so far has worked perfectly and been great to use. Thanks Pawel.
Google can sometimes hide small but useful projects like this behind the commercial component vendors and their “search engine optimizations”. Consider this a vote for Pawel. :)