Sure, it's been a while since we've seen a company trot out the 1990's "xtreme!" moniker for a product, but JBL's OnBeat Xtreme ($500) certainly lives up to the name. As a considerably larger and more powerful version of the previously-released OnBeat, this iPhone-, iPod-, and iPad-compatible audio system uses the same "weave" industrial design and rotating central dock, but makes improvements to pretty much everything across the board: the dock is…
