There are couple of cheat sheets about Ruby on Rails and related technologies can be found in the web. I decided to collect all of them (almost all) in one post just to keep them in mind. All of them are in full color PDFs or PNGs.

Ruby on Rails Development Cheat Sheets

JavaScript Development Cheat Sheets

Databases / SQL Cheat Sheets

Web Development Cheat Sheets

Other Cheat Sheets