I have a lot of ideas for this:
HYPER LINKER: Make 150 posts that each include at least 1 link.
MEGATHREADED PROCESSOR: Post at least 10 times in 4 different megathreads.
INB4LOCK: Be the last poster on a locked thread which is locked for at least a week.
INB4MOVE: Be the last poster on a thread before it is moved.
INB4FAILBIN: Be the last poster on a failbinned thread.
BETTER LUCK NEXT TIME: Lock a thread with 1-4 posts for at least a week.
POOL'S CLOSED: Lock a thread with at least 150 posts for at least a month.
ICEBREAKER: After posting on a thread that had not been posted on for at least 2 days, get 10 posts (excluding your own) within 2 days afterwards.
BLOCKLANDER: Post 400 times within the subforums in the "Blockland Forums" section (General Discussion, Suggestions & Requests, Modification Help, Clan Discussion, Gallery, Help)
FILE READER: Post 400 times within the subforums in the "Blockland Files" section (Add-Ons, Game Modes, Environment Files, Music, "Faces, Decals, Prints)
SOCIAL BUTTERFLY: Post 500 times within the Off-Topic subforum.
GAMER: Post 300 times within the Games subforum.
FORUM GAMER: Post 500 times within the Forum Games subforum.
EXHIBITION GOER: Post 200 times within the Creativity subforum.
BLOCKLAND'S LAWYER: Post 500 times within the Drama subforum.
FIREBUG: Make 100 posts involving politics anywhere and 100 posts on the Drama board.
CODE MONKEY: Make 60 posts on Modification Help and 200 posts on Add-Ons.
POSTING BOLDLY WHERE NOBODY POSTS OFTEN: Post 30 times on Gallery, 30 times overall in the Environment Files, Music and Faces, Decals, Prints subforums, and 30 times on Creativity.
DISTRESS SIGNAL: Start 10 threads overall in the Suggestions & Requests, Modification Help and Help subforums.