Can't find the rule list anymore, not sure if allowed to post multiple seeds or not per thread. Idea of thread is you post the seed your username gives you if it's anything interesting.
Argon: spawns you near a taiga village (confirmed 1.11 to 1.16)
allyourbasesaregone: spawns you on a peninsula of a island bisected by ocean, near a coral reef (1.13+ ?) Tested in 1.16 snap 18. Sheep on the island. Upright shipwreck spawned nearly above water, on a shoal/sandbank just south of the island.
I used my own mod, TMCWv4, since I don't play in newer versions and it would be much more interesting than vanilla 1.6.4. I spawned near -191, 35 (this may be different since I used a developmental version where I've made some changes to the spawn search from what the downloadable version has, but world generation is the same) in a Bushlands biome with Mega Tree Plains and Ice Plains to the west and Savanna Mountains as high as y=170 to the east:
Further to the east was a quite large Rocky Mountains, one of the largest that I've seen, with the highest peak at y=167:
To the north of the Rocky Mountains was a vanilla Mega Taiga, then Extreme Hills soaring to y=186, with a huge hollow in one of the mountains:
I came across a small plains village around 600, 230, and more notably, a TMCW Mega Taiga just to the east, and a larger one to the north of a Winter Forest (I have never found this biome in Survival despite having it been in TMCW since the first version):
Of course, the underground is just as interesting; the largest cave within 1024 blocks had a volume of 360,000 blocks. while the largest ravine was close to 250,000 and went all the way down from the surface to lava level, and two huge ravines intersect at around -20, 985:
Also, near 1024, 300 is a large complex of large caves, including the second largest cave by volume, at 177,000 blocks:
Here is a biome map (the grid is 256 blocks), a 3D rendering made with MCMap, and an underground map showing all "special" variants of caves, both covering a 2048x2048 area centered at 0,0 (the lack of caves near the center is due to a 512 block exclusion zone; there is a "NoExclusion" version which allows all types of caves to generate near the origin):
That said, you can see what you get in vanilla 1.6.4 here (from an old thread on the same subject):