Set the Wayback Machine, Mr Peabody! - Watched X amount of anime from the 70s
Tripping the Anime Fantastic - Watched X amount of anime from the 80s
20th Century Boy - Watched X amount of anime from the 90s
The Great Hunt! - Watched X amount of city hunter (maybe all the TV shows and 1-2 movies + 1-2 ovas or something).
Mechanization - X amount of Mecha Tags
We should have some metabadges at some point!
You are a Studious - Achieved X amount of badges related to Studio badges (ie, gained 5 badges such as JC Staff, IG Production, Toei Animation, etc)?
Trail of Bodies - Have the Stalker Badge + Left so many odd comments or something?
Exploding Blogosphere - have 2+ custom list badges + 2+ blog badges?
Multiple Duality - X amount of loved chars + X amount of hated chars?
Edit:
For manga stuffs:
Page Lover - Read 500+ Manga
Book Lover - Read 1000+ manga
Group Study - Read x amount of harem manga +
Group Study in Reverse - Read x amount of reverse harem manga
You've been decked - read x amount of manga with card battles tag