Here is a little update on my experience with the GPSlim 236 so far:
My setup is a Dell Axim x51v ($250 from Slickdeals), the GPSlim 236 ($80, but it is cheaper with this deal), 2GB SD Card ($18 from Slick deals), TomTom 6. Total Hardware Cost = $348
I have been using the setup on a trip to San Francisco, and I have become so attached to it that I can't imagine traveling without it ever again! It has taken me a couple of days to work out some quirks with TomTom, but overall it has been extremely smooth and the maps are incredibly detailed. I have used it to find hotels, resteraunts and sights all over the city. It also gives you the phone numbers for most of these places. Even after looking for 30-40 unique places, EVERY location was in the maps.
I was able to travel to Napa Valley, Sonoma, San Meteo and San Francisco without even looking at a paper map. It even lets you select between walking and car navigation. If you accidentaly overshoot a turn, the maps instantly gives you a new path.
The GPS unit's battery last a LONG time. I usually turn it on and leave it in my pocket all day. Once it connects the first time, it pretty much stayed connected all the time, even in heavy cloud cover and in a forest, and in my pocket. The only time the battery did die was after 11 hours of continuous use. The Axim's bettery only lasts about 2-3 hours, so I only turned it on when I needed it, then off when I was done. It only took about 10 seconds to reconnect to the GPSlim after being off, and didn't need any re-configuration (I never turned off the GPSlim, though). When I get home, I will buy a car charger for the Axim.
Overall my experience has been great, and I am very happy that I bought the unit when I did. If anyone has specific questions, I will do my best to answer.