Program an ATtiny 45/85 with Arduino IDE - The MIT High-Low Tech Lab posted a tutorial on how to program an ATtiny45 or ATtiny85 micro-controller using the Arduino IDE. This functionality is accomplished by using a subset of the Arduino libraries to add a set of core runtime source files to support the ATtiny45/85.
Arduino-Tiny - An open source set of ATtiny “cores” for the Arduino platform that enables Arduino users to work with the ATtiny84/44/24, ATtiny85/45/25, and ATtiny2313.
Using Dropbox to Centralize Arduino Sketches - Here is a link to a site that explains how to use Dropbox to centralize sketches. Using Dropbox to centralize your sketches allows one to work on the same file from multiple computers, back up the file, and keep a track of the different versions just in case you need to restore a previous version.