[Yarmark]

This is a nice screensaver, it automatically generates a 3D city on the fly and then flies you through it. It's free and is designed to run on older graphic cards.

Windows version: http://code.google.com/p/pixelcity/

Mac Version: http://pixelcity-screensaver.en.softonic.com/mac

How it's made and what it looks like -

[Xbcofega]

Nice! Thx for sharing.

[Gaiaakgyyyg]

Nice! Thx for sharing.

Not a problem, its actually kind of cool, it even works on my laptop which is kind of impressive since its a couple of years old. Works great though.

[lomonel]

Looks pretty cool. Thanks.