fastmail.fm. Their webmail is pants (all webmail save GMail is pants), but their IMAP service has been 100% bulletproof. Oh, and MobileMe for pics, but that's because I'm trapped in the MobileMe universe because the value of OTA contact syncing is just ... barely ... enough, and now most of my pics are there. Vendor lock in is easy; the first hit (when I was an employee) was free.