Well, the new Alpine double-din navigation is really good on paper and has an available ipod interface, but if you want ease of use and clean OEM-looking integration, you can't beat the Eclipse AVN 5495, with integrated 30gb hard drive.
They were discussing new product at SEMA a few weeks ago though, so if you're really in the market for it, I would wait until they unveil the new lineup, which should be demoing around CES time (first week in Jan) and release for the public by Spring.
"Good sound" is kind of a relative term because to an audiophile, they all kind of suck, but you can fix that with a processor like the Alpine PXA-H701 for the Alpine unit, or Rockford 3sixty for anything else. (you can actually use the PXA-H701 on any head unit, but for non-Alpine it requires an additional controller, whereas the Rockford unit uses a Palm device over Bluetooth).
-Ray