A good proportion of my e-mail these days has to do with the status of applications running on various servers around the place. Various Rails apps e-mail me every time an exception is thrown, and various Nagios installs e-mail me alerts.
It's getting to the point where my mailbox is pretty cluttered, and it doesn't mean anything any more when Thunderbird pings me to say I have new mail -- it could be a critical alert telling me a site is down, but then again it might just be some spam, or a pile of Ruby exceptions that have nothing to do with me.
I'm also working on enough different projects that I lose my 'state' quite easily; if I come back to one project after an absence of a day or two, or get pulled back and forth between projects due to e-mail/IM interruptions, it's hard to stay focussed.
I guess I want something that will prioritize things for me - let me tag stuff by project, associate e-mails with tasks etc. A desktop app that integrates with Remember the Milk and Trac, or something? Hmm...