I will probably get a Bluetooth GPS receiver before my next business trip. They're cheap; it's the mapping software that's twice as expensive.
With that in mind, I've found a "free" mapping package for portable devices (cell phones, Palms, etc). Earthcomber.com is like Avantgo, but provides location-based information.
You can download maps of counties, such as Whatcom (Sumas, Bellingham) or King (Seattle). The maps are somewhat crude in detail, especially when zoomed out. They don't take advantage of my Palm TX's high resolution. And they're not that useful for us non-USA residents, because the maps and info are limited to the USA.
But it is free. And I do make business trips to the USA.
(Go to the Earthcomber Web site, register, make an initial selection of county maps, download the software, synch-install on your Palm, and then try it out.)
Without a GPS, you can show on the map where you are, and then Earthcomber gets you information about local features from its built-in database -- things like the nearest electronics store or gas station. If you have wireless access, it can download a text-based route description between two points that you pick.
With a GPS attached to your Palm, Earthcomber will show where you are on the map.