I really love cheat sheets. In a lot of cases they can take the place of an entire manual. So I was surprised, given its popularity that I couldn't find a single-page reference for the arduino online.
I tried to make a sheet that captured all the things I hit the reference for while programming. What data type does the millis() function return? How long till that overflows again? How large can a long get? What baud rates can the serial handle?
Any other things you'd like to see added, send me an email and I'll stick them on Rev 3!
Edit: Thanks to Macca and TBAr for their feedback. Here's V.02b
Edit2: Thanks to others for their feedback. Here's V.02c!
Click for large version. For printable, check out the PDF at the bottom of the page
Thanks to the guys at Arduino.CC and also Fritzing.Org, whos images I shamelessly stole in making it. (I'm pretty sure it's all OK under the CC, but if not let me know).