This is one I've been using personally for a while now that I just polished up enough for a public release.

CondHail is a rule-based one-button hail program. You create a set of rules to match specific criteria about your target, then CondHail chooses a hail message based on those rules.

It registers one command: /condhail which is used for everything.
Type /condhail help for usage information.

Current version is 0.2.1 and you can find it here:
http://www.voupr.com/plugin.php?name=condhail

Please post in this thread for comments or suggestions.
Enjoy!