So I found this great site that tells you of trails and parks in North America.
Very nice!!!!! OFF ROAD LANDS (http://www.offroadlands.com/parks.asp)

Thanks for confirming the sad sad reality that the only thing within a reasonable drive is Rausch Creek!

Apologies..

this one's worthy of a sticky gaze!

Here's a good one for the western states; Colorado and Utah in particular:

http://www.traildamage.com/trails/index.php

As far as Colorado that list is very incomplete. There are a lot of areas not even mentioned. I can think of at least a dozen trails, mostly in Summit County and some connected to Park County that are not even mentioned. At least half of them could be driven by a Patriot.

And some of the most famous trails in Colorado like Imogene Pass, Black Bear Pass, and Holy Cross City are not even on the list.

Same here CWM. The Arizona list is very limited.

There is so much public lands around here it's crazy.

Check out this map:

http://www.nationalatlas.gov/printable/images/pdf/fedlands/az.pdf

Anything pink, light green, medium green, or yellow is open for driving. With the proper permits of course.

I haven't found a single source that is complete. Use multiple sources. Also, it gives you different perspectives of some of the trails that are the same in each publication.

Also, remember, that not all publications use the same trail rating system.

Add this to your favorites: http://www.offroadatlas.com/

I agree that there don't seem to be any comprehensive trail databases on the web. That's not necessarily a bad thing because it helps with crowd control.

There are a lot of hardcopy guidebooks available that provide fair to good regional coverage of the southwestern US.

I have found a lot of good trails by studying the DeLorme Atlas and Gazeteer. Topo USA and Google maps are also helpful. The Baja California Almanac is must-have for south of the border. None of them show every trail, there's no indication of locked gates/private roads, and there's no trail description or indication of difficulty. But not knowing exactly what to expect is half the fun. :)

Here's another site that may turn out to be useful: Dirtopia (http://www.dirtopia.com/wiki/List_of_States)

Australia

4x4earth.com.au (www.4x4earth.com.au)