I spoke to the man in the saloon about blowing up Megaton by planting a charge on the atom bomb in Megaton and come back to Tenpenny tower to detonate it. Doing this will very obviously destroy the town, which makes it a difficult decision to make. Blow up Megaton or do nothing? I don't feel like there is much left for this town to offer, but I don't want to risk losing out on some interesting story content later on in the game because I made this decision. What is the best thing to do?
I don't think there is much to lose by blowing it up if you have completed all of the quests here. However, there is absolutely nothing at all to gain from blowing the town up. You will gain a very large amount of negative karma for doing this. You will lose the chance to trade here in the future, but I don't remember there being anything major.
What I did was make a save before going into Tenpenny tower. I then went on and detonated the bomb in Megaton. The explosion brought the framerate on the PS3 to about -45 and once the explosion I was happy that I could restore the game save as doing so really did nothing worthwhile. I also killed everyone in the area before reloading the save because I got a small taste of that sweet negative karma and couldn't stop :P