I hate having to wade through useless forum posts like "wow" or "me too." It would be really cool if you could just click on the offending post and have it minimize, much like when you hit the "thumbs down" in Digg's comment system. Is Greasemonkey the way to go or is there some other way to do this?

Yes, but it totally depends on which forum it is.

Are there currently any scripts out there that do this? I tried looking, but I couldn't find any.

Well, it still depends on which forum it is. If you couldn't find it for the specific forum you're needing this for, there probably isn't a script that does this.