What are the useful/awesome 50/50 entries in high level matches?

[yetanother]

Seeing as there are nowdays a bunch of good attacks from the 50/50 now days (Erberth Santos and Luiz Panza are lethal with leg locks in the gi from there) as well as bunch of cool passes from Rafa Mendes I'm thinking that I should start playing with it. People put me there when I try to berimbolo them and they might as well pay a hefty price for doing that but if I develop it getting on my own initiative would be great.
What ways of getting to the 50/50 should I look into? Stuff that's used by top level guys would be best.

I train under IBJJF rules (mostly in the gi).

 

[mataleaos]

Anytime you are in inverted guard or you're granby rolling, it works well if you roll towards their outside leg and shoot up a triangle. If you watch a lot of old pre black belt Ryan hall matches when he would shoot the triangle choke from inverted guard or when he was granby rolling, people started standing up. That's when he shot the same motion and started getting the 5050 instead. I don't have any links on hand but if you watch his old [urple and brown belt matches you'll probably see it a lot.

 

[MotivatedPenn]

Ryan Hall has an entire DVD series on the position. It includes entries as well

 

[ijustwannasurf]

Watch some Cavaca matches. He pulls 50/50 against high level opponents quite often (in the gi, at IBJJF events).