Coding regrets - i've had a few. Already
http://www.artima.com/forums/flat.jsp?forum=270&thread=247176
http://www.sans.org/top25errors

That would be:

CWE-20: Improper Input Validation

#1 killer of healthy software, apparently (the article is a shill for SANS remember)

CWE-116: Improper Encoding or Escaping of Output

Computers have a strange habit of doing what you say, not what you mean. Insufficient output encoding is the often-ignored sibling to poor input validation, but it is at the root of most injection-based attacks, which are all the rage these days.

CWE-89: Failure to Preserve SQL Query Structure (aka 'SQL Injection')

CWE-79: Failure to Preserve Web Page Structure (aka 'Cross-site Scripting')

Cross-site scripting (XSS)

CWE-78: Failure to Preserve OS Command Structure (aka 'OS Command Injection')

When you invoke another program on the operating system, but you allow untrusted inputs to be fed into the command string that you generate for executing the program, then you are inviting attackers...MORE >>

CWE-319: Cleartext Transmission of Sensitive Information

If your software sends sensitive information across a network, such as private data or authentication credentials, that information crosses many

CWE-362: Race Condition

Attackers will consciously look to exploit race conditions to cause chaos or get your application to cough up something valuable...MORE >>

CWE-209: Error Message Information Leak

If you use chatty error messages, then they could disclose secrets to any attacker who dares to misuse your software. The secrets could cover a wide range of valuable data...MORE >>

CWE-119: Failure to Constrain Operations within the Bounds of a Memory Buffer

Buffer overflows are Mother Nature's little reminder of that law of physics that says if you try to put more stuff into a container than it can hold, you're...MORE >>

CWE-73: External Control of File Name or Path

When you use an outsider's input while constructing a filename, you're taking a chance. If you're not careful, an attacker could... MORE >>

CWE-94: Failure to Control Generation of Code (aka 'Code Injection')

For ease of development, sometimes you can't beat using a couple lines of code to employ lots of functionality. It's even cooler when...MORE >>

CWE-285: Improper Access Control (Authorization)

If you don't ensure that your software's users are only doing what they're allowed to, then attackers will try to exploit your improper authorization and...MORE >>

CWE-259: Hard-Coded Password

Hard-coding a secret account and password into your software's authentication module is...MORE >>/