I just finished reading this wonderful fan-ficton that crosses over Burn Notice and MLP. It's called Banishment Decree. I suggest you give it a go.
Banishment Decree Prologue
Eh, I prefer reading "X Meets Y" crossovers instead of "X parodies Y" crossovers.
Speaking of USA shows, there's a
REALLY good Psych crossover (yes Shawn in Equestria). The first couple of chapters seem a little off at first (mostly because of the way Shawn expresses his inner thoughts, something you're not used to seeing in the show), but then it hits its stride and feels true to both shows. It's definitely "OMFG SOMEBODY FUND IT!" tier.
A couple others I've been tracking
The Elements of Harmony and the Savior of Worlds
An Epic G1 crossover. It's so good and believable (in a headcanon way) I ALMOST want to watch G1 cartoons to understand it a little better.
The Animation Bureau
This fic is just all around silly and not really cohesive compared to the fics above, but it's a fun read. It's like a crazy futuristic mix of Who Framed Roger Rabbit and South Park's Imaginationland. It features Lauren Faust as an agent who helps keep the peace of Animated worlds. Yeah.. it's weird, but silly and fun!
My Little Enterprise
A daunting MLP/Star Trek/Who Mega Crossover. It's got its fair share of technical problems like author jumping the time and place on a whim and boring OC Ponies, but the saving grace is its 4th Wall breaking, "Galaxy Quest-like" twist that I won't spoil here.