DrivethruRPG would be much appreciated. Here's a few that I've found on my internet travels.
"Versatility is the name of the game for USR; it’s the kind of system that begs you to try new settings and scenarios...I highly recommend picking up the PDF of USR." - Ted from Dos Tacos Libres (full review)
"I'm not overly fond of statistics and too many tables of stuff, nor do I have the space for miniatures and maps, so I went with the USR (Unbelievably Simple Roleplaying) System for this, and it worked out really well. It's got the right mix of dice-gaming and imagination to be amusing and not too heavily skewed in either of these directions" - Promethius on Open Pandora Forum (full review)
"Are you looking for an unbelievable simple roleplaying game? Then you should check out USR by It uses very simple but astonishingly effective mechanics. Damn, I wish I came up with this!" - Michael Wolf from Stargazer's World (on Google+)
"[A] fun system from an awesome guy." - Brent Wheeler (on Google+)
It's great to see people having fun with USR. If you're a blogger who has run a game, let me know how it went and I'll give some link love in return.