Pighixx has created several pinout diagrams, and posted them in the Arduino forum. They’re for the Arduino UNO and for several ATMega microcontrollers, such as the ATMega 328 and the ATMega 1284p.
These diagrams provide a clear picture about how to use each pin of the board and can be used as real “cheatsheets” for your own DIY projects.
While on his site, I also found quite a few other useful pinout :
Source : Arduino forum via Arduino