Not possible with the current version...

I don't know how useful it would be to highlight sticky threads- they're already sticky... Usually you don't want to make them look different then regular threads or people learn to ignore them.

Based off number of replies or ratings ("Hot threads") I could see being more useful but I'm not sure if it would be wise to add it to this mod or make a separate one.

Looks like a useful mod but I have a question.

Maybe I missed this but if I select, say, the admin group as the one that highlights threads, does that mean that EVERY thread an admin creates will be highlighted or can he select it for individual threads?

You can't choose individual threads. It will highlight every thread by that usergroup. You can choose not to highlight in specific forums though- for example no need to highlight admin threads in an admin-only forum.

Ahh.. OK. I was looking for some way to simply highlight one, or more, particular threads. Is there a mod that can do that?

Not that I know of.

I was considering adding an option that would allow highlighting based on a thread prefix but I haven't started that.

What would be good is an option in the moderator dropdown box, the one where you can stick/unstick threads, delete them, move them and so on. Add an option to highlight them.

Not sure if you can do that, but it would be handy.

I don't feel the overhead required to make it per thread (new database fields, new form inputs, etc...) would be worth it.

Fair enough, I have little idea of how much work would be involved in something like that.

Will this only highlight threads where the selected usergroup starts the thread, or will it also do it if the selected usergroup replies to a thread started by a non-highlighting usergroup? I have need for an ability to highlight all threads in which a specific usergroup has posted, not just started a thread.

This only does if they are the thread starter. I don't see a practical way of doing what you ask- it seems scanning every post in every thread on a showthread page would use a lot of resources.