I check Loony_BoB at yahoo.com constantly throughout the day, and I have Y! Messenger which alerts me when I get new mail.
I check my @computacenter.com (work) email almost once every two minutes at work because at least 50% of the communication done at work is via email.
I check crikey_moos at yahoo.co.nz about once every month or two, or whenever I sign up for something using it (basically anything I don't want my main email account used on).
Loony_BoB at eyesonff.com redirects to my main email anyways. I don't think I have any others that I really remember aside from dptowns at yahoo.co.nz (or was it .co.uk?) which I only use for business reasons when I can't use my computacenter email (ie, at a PC that isn't secure).