Although there is no sign-up bonus for the United College Plus card, you do get a 10,000 mile bonus upon graduation. Perhaps you can consider it as a "post-sign up" bonus. Also there is a 2500 mile bonus for your first and third paid United round trips flown by July 2003, though I suspect the deadline will be extended (it was last year and the year before).

I've been very happy with the UA College Plus card, and I got all the bonuses including the graduation one without any problems.

Alex