This is some really cool freeware (well, cool if you're some kind of IT geek). Anyway, Redmond Magazine recently had a review of NetWrix Password Expiration Notifier. In a nutshell, it e-mails users when their Active Directory password is about to expire. This is huge for companies with remote users who only use webmail, local users that don't logout for weeks at a time or Mac and Linux users that need Windows resources. The price is perfect for the base model and for more bells and whistles, prices start at $350 and climb upwards with the number of users.
Ps. Check out NetWrix's array of Freeware.