I build Userstyles principally for :
- Firefox.
- WideScreen (1920x1080) adaptation:
More things in the window, less scrolling. - Dark Gray style:
better for night surfing. - Site Navigation:
Tweaks its Interface by moving many things. - Bypass Sites Limitations
See too:
Decembre [GreasyFork].
I publish my Greasemonkey tweaks here:
Decembre's Pastebin