Nothing like filling out an InfoPath form and having information like First Name, Last Name, Title, Phone number already filled in for you. If you're using InfoPath 2007 & MOSS this is going to be a snap.

 I found this article very helpful:

http://blogs.microsoft.co.il/blogs/itaysk/archive/2007/04/05/InfoPath-_2D00_-Get-the-current-user-without-writing-code.aspx