There are all kind of HD (HQ, HiRes or High-Res, same meaning different spelling) (re-)texture packs and different (re-)models of pretty much anything on Fallout 3 Nexus. If you still don't know it, Fallout 3 Nexus is the main source for Fallout 3 mods, models and textures.

Running with higher resolution texture packs as always results in higher demand on your computer. Be sure your PC can handle it, don't install all  texture packs at once. Install one pack at a time, test it out then continue with the next.

Long story short:  I'm quite fond of 4Aces DLC high-res textures [direct link]. Enjoy!

Addendum 17.05.2010:
Like a lot of people who have large amount of mods, especially texture mods, I've experienced frequent crashes to desktop. This is due the fact that Fallout 3 is a 32Bit game which in turn results in the usage of a maximum of 2GB of RAM. If you have, say 4GB RAM or more, Fallout 3 makes no use of it.

Fear not, there has been a solution since last year which I completely missed up until a few months ago. Large Address Aware Enabler for FO3 or FO3 RAM Boost. Either one works and reduces the crashes to almost a nonexistence.

Some Fallout related videos:

Related posts:

1. Must-Have High-Res Texture Packs for Fallout 3
2. The Hillbillies invade Fallout 3 – “Point Lookout” HD gameplay clips!
3. Fallout 3 goes into the Pit – “The Pitt” HD game play clips!

As you can probably imagine I'm currently playing the 3rd new DLC, "Point Lookout". It's Bethesda's 4th one and many more may come (I guess I was wrong, 5 is enough!).

Point Lookout takes you to an isolated island, it is Fallout 3's equivalent of Point Lookout State Park. An amusement park, with a huge carousel surrounded by a damp swamp and an old lighthouse overlooking it. It gives off an eerie feeling.

And the bonus: remember the Pint-Sized Slasher? Perhaps Point Lookout, Maryland is where the Slasher originated.

The whole DLC is somewhat horror / thriller themed. The nuclear bombs did not fall on Point Lookout, but the island was simply forgotten and left to its own resources.

New monsters are present, the Swampfolk, inbreed hillbillies with hostile attitude toward the player, such as Trackers, Creepers/Scrappers and Brawlers/Bruisers. Even a swamp variant of ghouls and mirelurks. Oh, and a new set of humans too, the Tribals.

Of course new quest-able perks are added, although nothing huge, still funny to have and weapons such as double barrel shotguns, axes and shovels.

Because so many Confederates died during the American Civil War on Point Lookout, you'll find Confederate Hats by the thousands.

All in all, I can only recommend this DLC! The 5th DLC "Mothership Zeta" is coming in July August, and will supposedly involve the crashed alien ship and not so friendly extraterrestrials.

Screenshots and Gameplay clips after the break.

Screenshots:
http://www.the-screenshots.com/Fallout3/Fallout3_PointLookout

Gameplay clips:
The Local Flavor (Calvert's Mansion): Part 1/2, Part 2/2
Exploding Calvert Mansion

Related posts:

1. Fallout 3 goes into the Pit – “The Pitt” HD game play clips!
2. ‘Dismembering for Dummies’ by X-Men Origins: Wolverine [HD gameplay clips]
3. Demigod – Can you smell what “The Rook” is cookin’? [HD gameplay clips]