I'm sure that there's quite a long list, but two things I've bumped into with using the MySQL protocol are:
1) We don't have SHA1 - I know there are people working on this. I've done a version that is as close to the reference C implementation as I could make myself keep it. This may be useful as a check for others doing more efficient implementations. If you want it, please let me know. Related issue is should we have std.digest instead of std.md5 2) We don't have an off-the-shelf Socket class for Unix Sockets Steve