Garmin offers a great variety of gps devices. most of them do allow you to import topo maps. only problem with the garmin devices is they use a spefic topo program. nice thing is a lot of times you can by a package that has the topo program included, otherwise you are paying around $100 to buy it alone. regardless a GPS has helped us tremendously in our scouting efforts.
The GPS unit we prefer is the Garmin 60CSx. It has just the right amount of applications that are perfect for the hunter. When purchased, we got the package that offers the topo maps. There are other less expensive GPS models by garmin that will also do the trick. If you dont mind spending some extra cash, the Garmin Rino has a two way radio feature that is great to have when in the field with someone else. You do not have to worry about carrying both a radio and your GPS, it also has a neat feature that shows where your partner is when you are talking. (This is only Rino to Rino communication though).
Another option to consider if you would like to import ariel photos is the Bushnell Onix. Although a great feature, it tends to run slower than just a traditional GPS because of the added information it has to process.
Oh, and the other nice part of the garmin topo program is that you can transfer your maps routes and waypoints to google earth. you just cant put google earth on your device.
Hope this helps. if you have any other questions feel free to email us at firstname.lastname@example.org