Here's a SotC attempt:

First time I've read about the Boomer achievement I thought it was for Gears of War >.>

Besides Witch, Tank and Hunter I forgot all other Left 4 Dead zombie names.

How about badges for how many wall posts you have with a certain person? Like:

Making friends- 10 wall posts with 1 person

Joined the party!-100 wall posts with 1 person (Final Fantasy)

Iron Bond- 500 wall posts with 1 person (Cave Story)

Inseperable-1,000 wall posts with 1 person 

I have some designs for the other two but like I said earlier I'll add them later when I have more time

How about this for the 'Iron Bond' one?

https://lh3.googleusercontent.com/_LVdqM5thrfU/TaCG-_9HO4I/AAAAAAAAAC4/GRmcKKUmGXg/s288/Cave Story.jpg

And this for the 'Joined the Party!' one:

https://lh4.googleusercontent.com/_LVdqM5thrfU/TaCIXo6heTI/AAAAAAAAADI/Jn-_MoehKYw/s288/FF.jpg

Torillian already did it, but you just need to remove the ".th" part from the picture's link.

So... I'm going to be a jerk face and try to reclaim the "Can't Stop Me Now" badge for Sonic!

Also, I really dig Seece's holiday badge idea... so much so that...

Valentine's Day

(Doesn't get much sweeter than this!)

St. Patrick's Day

(Clover Studios! Get it?)

Easter

(Jazz Jackrabbit!)

Mother's Day

(Mother Brain, it's in the name!)

Father's Day

(Big Boss, the ultimate daddy. )

You're not being a jerk face, the rules are that the best design wins and nothing is final until Brett needs the designs.

For 'One of a Kind':