If you're looking for the latest in miniature mics check out Samson's Airline Micro at
The receiver is a little larger than a cigarette lighter and the transmitter fits behind one ear like an older hearing aid. The mic itself is shaped like the Contryman and sits on one cheek.
Someone asked for the best microphone. That is kind of like asking who your favorite singer is.
For clarity you can't beat the Crown microphone or the Contryman (sp?), each of which can be ordered without the receiver to hook into something you may already have. The Crown is bulky and has a big foam ball that sits right in front of your mouth. Great for singers and developed for Garth Brooks. The Countryman microphone is the style that has a teeny tiny flesh colored mic and wire on one cheek and a wire that grips one ear. Both use wires that run down to belt pack transmitters. I find that the Countryman works best when taped onto my face.
If you play a guitar or just don't like the belt pack check out the Samson Airline system. It was designed for aerobics instructors and has the transmitter in the headband. The sound isn't bad. It is the mic of choice for Dennis Lee and it was what I was using and will probably replace. (Though I would love to try the micro.)
If you do a lot of shows it is GREAT to have a built in receiver and portable PA system, such as the one Axtell is developing. Receivers don't seem to wear out very fast. If a mic doesn't work it is almost always one of the wires. (I just bought another mic cable yesterday to replace one from 3 months ago! This time I bought a Monster Cable brand that has a lifetime warranty.)
Other brands that have good reviews are Sennheiser, Audio-Technica, and Shure. However, make sure you are getting their better mics. As mentioned before I was paying for a better receiver and got the $50 Shure mic in the $420 package deal. Not what I wanted. They do have a $180 microphone. Red reviews for products like this at Guitar Central, ABC Music, Harmony Central, and Musician's Friend. I think Gear Net may have reviews as well. So narrow down your choices then see what others say. Check at least two sites for reviews because you don't know how they may screen them.