I see a few people have their sites set up like this: www.sitename.com/tag/tagnamehere

Is there a way to make the tags archive this way, so as to avoid the nonsense URL that the search result method produces? Or are these people just using categories and calling them tags?

I don't think mt ships with rewrites for the tag search urls, if that's what you mean. When you see that, the blog owners have probably found a plugin to do it for them or are using mod_rewrite on an apache server... it can be pretty complicated if you're not familiar with regular expressions. Do a google search for mod_rewrite to check it out, or maybe someone could post the rewrite rules they're using here?

No plugin I've ever been aware of. Tag pages are always searches, so it'd be a rewrite to hide the URL. There's a recipe in the old beta blog under the "Beautifying the tag search link URLs" header. Keep in mind your rewrite may be different(obviously) depending upon what URL you want.

Ah ha. That is probably what I've been seeing, and should work nicely. Thanks!