Sure thing.... I'm using quite a lot, but here are some of the ones I consider essential.
Skyrim HD textures... Official package, which you update through Steam.
Glorious Grasses... quite a frame rate hitter, but worth it if you have the power.
http://skyrim.nexusmods.com/downloads/file.php?id=9185
Vurt's Floral overhall... I use the default aspen textures, but the rest are Vurt's.
http://skyrim.nexusmods.com/downloads/file.php?id=141
Pure Waters... there are other good ones too, such as W.A.T.E.R
http://skyrim.nexusmods.com/downloads/file.php?id=1111
Better static meshes.
http://skyrim.nexusmods.com/downloads/file.php?id=8655
Enhanced distant terrain.
http://skyrim.nexusmods.com/downloads/file.php?id=1598
Realistic Mountains
http://skyrim.nexusmods.com/downloads/file.php?id=13785
And ENB which is the main thing for changing how the games colour and lighting look... there are so many configs out there, and it depends on whether you like a natural look, or something more fantasy.
Check out the ENB Skyrim forum to see some of the work, and shared links.
http://enbdev.com/enbseries/forum/viewforum.php?f=14
I'm using a modified version of TV_ENB.