This is so cool! I'm definitely getting a Holga. It gives such a cool atmosphere to the photos. And you can get one for about 20£ on Ebay!
Holga Site:
http://shop.lomography.com/shop/
A few examples of pictures taken with Holga:
http://parallelsthroughimage.com/?p=159
There's also another one called Diana..It's only 120mm though which is a bit expensive to develop.
http://www.lomography.com/diana/
http://members.aol.com/hpargotohp/di_rh.html