The crack dictionary generator engine might be able to help you here. Instead of having the password generator use crypt, md5, or sha1, code up an "encryptor" that is an identity function: f(x) == x.

The last time I used it (I was a security admin, it was my job :), it had a pretty decent l33t sp34k module, as well as concatonation, misspellings, and other useful rules. Additionally, if you want to generate your own rules, the ruleset language is pretty easy to learn and use.