Firstly, IBM developerWorks has this Python 101 cheat sheet. Then there's a Domino URL Cheat Sheet which explains the URLs constructed by the IBM Lotus Domino server task to access servers, Lotus Notes databases, and other Web site components such as attachments and image files.

Some other cheat sheets for IBM technologies can be found via this developerWorks search for the term "cheat sheet".

Since Firefox is so popular, we certainly should add this Mozilla Firefox Browser cheat sheet to our toolkit, shouldn't we? And in deference to its share in the browser marketplace, here's an Internet Explorer 7 Quick Reference Sheet.

And because it's even more popular, there's this Google Cheat Sheet -- How to refine and improve your Google search, how to carry out arithmetic, how to get search results back from a single site, etc (with links to more detailed Help pages).

For example, the hypotenuse of a right-angled triangle with sides of length 3 and 4 is found by entering into the Google search bar: ((3^2) + (4^2))^0.5 and to search for "firefox" on the iTWire site you would enter: firefox site:itwire.com

With Linux/Unix being so inscrutably cryptic, it's not surprising that there are numerous Linux cheat sheets available, such as this and this and this and this -- to mention only a few.

If you're a fan of the vi editor, there's this Vi Cheat Sheet (and I'll bet there are lots more).

We could go on endlessly with this cheating business!

Let me point out the Cheat Sheet Roundup - Over 30 Cheatsheets for developers by Peter Freitag (pretty comprehensive).

Concluding with the daddy of them all: Cheat-Sheets.org which modestly describes itself as "All cheat sheets, round-ups, quick reference cards, quick reference guides and quick reference sheets in one page. The only one you need."