Backgammon Mania that I haven't tried yet, Jewelrumble 2 (jewelquest clone but they don't make jewelquest for bb) Wordcaster, Sudoku, Sudoku Master, Majong Solitaire and Sol Mania. I play Sudoku, Majong, or Sol Mania as a way to get to sleep at night. Jewelquest is fun and easy to put down if you need a filler app for between meetings when you don't have time for much else.
Many of the games are a way that I get people involved with my Blackberry so that they can play with it and get excited by it. It also keeps teenage relatives busy so that I can carry on a coherent conversation with their parents.