BG Radia Z1. MSRP $600
Phenominal sounding speaker. It's tweeter is used in this entry level pair all the way through the $16,000+ pairs from BG. It's an incredible sounding product*.
*If you have a sub!
http://bgcorp.com
Review...
http://www.audioholics.com/reviews/speakers/bookshelf/bg-z-1
An article in Stereophile (NOT recommended as a be-all-end-all) once said that the tweeter in this speaker tested better than those found in many speakers in the $50K range. The Z1 is on their recommended components list & I do not recall seeing BG advertise with them (or anyone else really). Point being: Even for a cheap(er) speaker by their standards, they respected it.
Here's another link to a test on the BG tweeter compared to others...
http://www.zaphaudio.com/nondomes/
Obviously, there's much more to a speaker than just a tweeter. However, my experience with this piece is that when tuned with a good sub it makes for an excellent 2.1 channel rig. BG products, in my opinion, are very special sounding products.
Any questions, please ask!