I'd like to strongly second DOCUMENTATION as a major item.

Theres nothing more annoying in the world then inheriting someone else's code to find out that there is no documenation on how they implemented their solution.

Comments are fine but they dont describe the architecture of the program, what servers are used, who the contact people are, what the business goals of the app are and more.

document, document, document!

The days of the adhoc hacker are gone. coding is a "profession" and should be treated like all other business initiatives.