Here are a couple of excellent websites which post a LOT of content about Arduino/ATtiny related topics.
http://jeelabs.org/
This is a blog run by someone who has invented their own platform similar to Arduino but called a JeeNode. The main difference is that a JeeNode includes an RF link. This is actually pretty cool as a complete JeeNode is only EUR18.50!
http://hackaday.com/category/attiny-hacks/
This site is frequently updated with interesting hacks which people have built around ATtinys.
