My favorite toy is Nokia's N810, a diminutive WiFi- and Bluetooth-enabled Linux-based touchscreen tablet computer. It connects super-easily to hotspots, has a decent if unremarkable pair of speakers, and runs a wide variety of open source Maemo applications.
Of late, I've used it a few times with my Verizon EVDO USB card, a Cradlepoint Technology battery-operated wireless router, and my Jeep's sound system to create a mobile Internet radio (together, they're smaller than most portable radios). I've driven from downtown Washington, DC to both Dulles and BWI airports listening to my former station in Washington State without a dropout.
Now I see that Nokia has introduced in the U.S. a WiMAX edition of the N810, and better yet it supports the 802.16e, the mobile flavor of WiMAX. It's intended for use on Sprint's Xohm network (Washington, DC will be, or perhaps already is, a test market). So since its range should be similar to EVDO when it's rolled out, one might be able to omit the mobile router. According to the Xohm article in Wikipedia, the intent is to merge it with Clearwire. I was a Clearwire customer back in the Northwest and loved it. It uses an early flavor of WiMAX and I was able to get good WISP service five miles from the transmitter using only a small indoor antenna perched in a window.
Lastly, my Jeep's sound system already has a USB port on the front panel, and Cradlepoint's technology makes connecting 3G or 4G cards very easy, so adding EVDO or WiMAX capability to car radios is just a matter of software and should be a no-brainer. I've written here previously that I think a great path to that is marrying it with HD Radios using SMIL and listeners can be their own programmers. --Dennis