Writing Testable Code

Check out Misko Hevery, the clean code talk guy's guide to writing testable code:

http://misko.hevery.com/code-reviewers-guide/

The page itself is a 5-minute read but download PDF for a more detailed explanation of the rationale for these guidelines, which are sort of a common realization among folks who have gone through the trials and tribulations of extensive unit testing.

There's also quite a bit of other interesting stuff on his blog, including: augular, a RAD platform for developing CRUD apps on the web with only HTML (no server-side, no SQL); and CoffeeScript, a terser way of writing JavaScript.