KeePass has a really nice passphrase generator with some excellent fine tuning options.

It would be nice to have a small box where the user could enter characters NOT to use in the generated password string.

For instance, having quotes " in the password often leads to cut off passwords at this character in some circumstances. Excluding such characters manually would be really handy to avoid that.

I'm considering trying my hand at writing a patch for this in the next few weeks if nobody is up for the challenge (but I've never programmed in C++ before).