I've been to Gerlach-Empire, NV two towns in the desert with a population of about 300, and I've heard that these two towns are the most remote in the lower 48, ie the furthest towns from any other town (the nearest town from there is about 65 miles down the road).
Callao and Trout Creek near the Utah/Nevada border are even more remote than these by quite a large margin. I believe Trout Creek is well over 50 miles from the nearest paved road. On the other hand, maybe these two communities are too small to be considered "real towns".
Anyway, I guess by United States standards I've been to a lot of remote places.
Here's just one:
http://www.summitpost.org/article/27288 ... -arch.html
I've been to quite a few remote places in Northern Arizona, Southern Utah and Northern Wyoming as well. I guess many of the places in Montana and Idaho I've been are fairly far from roads, but by Montana and Idaho standards wouldn't be near the most remote areas of those states (such as the heart of the Frank-Church or Bob Marshall Wilderness). In places like the North Cascades, there are plenty of remote areas, but I've stuck mostly to trails so haven't been to the really remote sections. Unfortunately in recent years (10+ years) I've been mostly confined to taking vacations in winter only so haven't gotten more into those areas, though I really want to.
Other than places in Dinosaur NM, I've never been to a place in Colorado that I would consider to be remote. Some people speak of places like the heart of the Gore Range, Never Summers or similar areas as being "remote", but in the rest of the Rocky Mountains they would be considered to be extremely popular so I always chuckle when I hear such things.
Outside of the United States, the most remote populated place I've been to would probably be Paudwar Nepal, which is seldom visited by outsiders.
Parts of Colombia seemed really remote to me, but if I lived in the area, it might seem different. I've been told that I was the first American to visit some places in some of the more remote regions of Uganda so to me some of those areas were really remote as well.