So if you are a Fallout fan as I am there can really be nothing better than a mod that joins Fallout3 and Fallout NV into one seamless whole . It is still Alpha, though it has been worked on for many years now and is incredibly stable, even when I use AMD's fancy new driver and set my resolution at 2560x1600 /w 4XAA run Ultra NMC texures along with Vurts overgrown wasteland and 120 misc mods(still getting 40-60FPS with 290x+3570K. Most of these mods are specially rebuilt to use the TTW properly, and there is ample step by step instructions for even a beginner modder. Some even have hady scripts to do the work for you.
Plus you can visit worldspaces like iceland,boulder dome, orions gate anything (a new group is working on a FO1-FO2 worldspace as well that should be compatible) . Even take a vertibird with converted scripts to work everywhere. It is an amazing amount of work and if you are an excellent modder there are even cash bounties for hard to convert mods. I think there is only one unclaimed at the moment.
I have nothing to do with this project other than being a huge fan and supporter. And as a bonus the mod authors are usually online and more than willing to help set things up.