The discovery continues...
So, defying all gaming logic, you can two-in-one Guile's Flash Kick into his Super (or Ultra), which, in my opinion, is the hardest input in the game (even beyond the 720°). For reference:
Charge D, U + K -> Flash Kick
Charge DB, DF, DB, UF + K (or KKK) -> Double Flash (or Flash Explosion)
Well, the Flash Kick (at least the Short version) can be combined with either the Super or Ultra by using the following input:
Charge DB, UF + K [-> Flash Kick], DB, UF + K [-> Double Flash]
It doesn't make any sense, since there is no DF input, unless the real necessary input for the Double Flash is Charge DB, F, DB, UF + K, though that is definitely not stated in his movelist as such. Craziness, I know. Not much point in the Ultra at all, as, in my experience, the last strike won't hit. Not really sure how the priority of the Short Flash Kick compares to the Double Flash, but at least it's an extra hit.
Another neat combination I picked up in the Trial Mode is Zangief's
Double Lariat -> Focus Cancel -> Backdash -> EX Banishing Flat. Not a great way to spend 3/4 of your Super Meter (*cough*three EX Spinning Piledrivers*cough*), but pretty impressive. You've got to be pretty quick to nail the EXBF before they hit the ground. I also learned that a fully charged Foucs Attack with dash follow up leads to whichever throw you want. (Ideally, the UAB, natch.)
Oh, and I've looked into El Fuerte's Run-Stop-Fierce loop. Definitely not something I can pull off at this point...