A useful resource: gmane.org
There's a lot of useful mailing lists out there; far too many to actively subscribe to, especially if they're all going to funnel into your inbox. And often you're not sure how interested you're going to be in a particular mailing list, or it's only interesting some of the time or for a few discussions. Plus, let's be honest here: most email clients don't deal very well with lots of email messages.
Enter gmane.org, where they subscribe to almost every open source or technical mailing list they can find, gateway them all to news groups, keep them around forever, and then let you read and search them through NNTP, RSS, and several web-based views.
This makes gmane.org an ideal place to dip your toes into new mailing lists or mailing lists you're only interested in every so often. Even for mailing lists you want to read regularly, using gmane.org has the advantage that good news readers are simply better than almost all email clients for that sort of message volume. (And since gmane.org has each mailing list in its own newsgroup, you don't need to disentangle ten mailing lists and your regular email, all in one mailbox.)
There's more gmane.org features, but I'll let you go to their website to read about them.