In some more list-it fashion, CNET has compiled an index of the top must-have titles for the PSP. The ten games are filed in alphabetical order, so there's no other hierarchy to it. If you are a new PSP user, you might find this useful. However if you're a veteran, chances are you already have these games.
At any rate, the list still provides a solid vantage point to see what's hot on the portable system.