What domain do you use for email? Your personal blog or site domain, a business domain (your own company or one you work for, or perhaps a school domain), or just a standard email service like Gmail?
And, if you're using your own domain, what do you use to host your email? Google Apps for your domain, Exchange, your own hacked email server, carrier pigeons? If you're using a standard email service like Gmail, why? Should have a lot of interesting responses!
In order to get gmail to check my POP3 account regularly, I use cron to send a dummy email to that account every 10 minutes. The dummy e-mail immediately gets deleted, but google's algorithms check POP3 with a frequency dictated by how frequently you recieve e-mails. Without this set-up it sometimes goes 1 hour before it checks the POP3 account. Using this set-up it checks every ~3-5 minutes which is sufficiently fast. I sure wish my university would just give me IMAP access, though.