I was waiting for someone to ask this question. At last! 
While I appreciate the whole IMDB Top 250 list, my actual favorite movies (i.e. the ones I end up watching again and again) are:
Showgirls - I found out only after watching it that it's considered to be one of the worst movies ever. Personally I think it's friggin' awesome. It has pretty young ladies, Agent Cooper, passion, betrayal - everything.
The Fifth Element - comedy, thriller, sci-fi and Bruce Willis is in it. Well, it had me at Bruce Willis.
Bowfinger - less known but absolutely brilliant Frank Oz's comedy. Highly recommended for viewing after dealing with SAP Support.