Here's a Super Turbo trick that Nekohashi put on his blog a few years ago. The original post is here. Info about safe jump option selects has been widely disseminated for SF4; I thought it'd be nice to post some nitty gritty for SF2.
"Built-in Dragon Punch" and "option select Dragon Punch" are more or less interchangeable. The idea is that the DP motion is "built-in" to the previous attack.
"Hit stop" is the brief (about a quarter of a second) freeze for both characters when an attack hits or gets blocked.
Translation note: I paraphrased some of this but kept Nekohashi's voice; first person comments below are his.
For this trick you do a safe jump on your opponent and then if they do a wake-up attack you'll beat it with a DP. If they don't do the wake-up, however, after the jump attack is blocked there's no DP. Safe jumping is well known amongst SF2 players, but with this built-in DP you can further enhance the technique. The theory is that if you blocked [after safe jumping] you could have DP'ed.
1. Input the safe jump attack
2. Reach the moment for the safe jump to hit or get blocked
3. Complete the built-in Dragon Punch command
4. Safe jump kick whiffs as opponent does wake-up reversal
5. Since the safe jump kick didn't make contact, the whole sequence is shortened by the hit stop duration so you get a Dragon Punch as you land
We want to put this to use against wake-up attacks that can't be punished or to crush gambling wake-ups + inflict damage (+ loop.) Ultimately the goal is to discourage any wake up reversals and leave them with no choice but to block the jump kick.
You have to input the command for the Dragon Punch extremely quickly in conjunction with the safe jump kick. For a safe jump roundhouse with a built-in jab dragon punch the actual button presses should be happen with a quick "TATAN." They should be about one to six frames apart — do it as fast as you can. If you think about the timing for canceling a jumping punch into an air HK with Ken, this is similar to that. In the event that your opponent blocks your safe jump kick you must finish the Dragon Punch command before your feet touch the ground.
Some notes about Ryu's built-in DP vs. various attacks.
Green: option select OK. Red: option select NOT OK.
Vs. Ryu: Hurricane Kick, Dragon Punch (trades), Super Fireball (delayed super freeze makes this ok)
Vs. E.Honda: Headbutt, Sumo Drop, Super Headbutt (super freeze means timing is difficult)
Vs. Chun-Li: Super (no safe jump vs. Tenshokyaku [RH version])
Vs. Guile: Flash Kick (DP generally loses to Super Flash Kick)
Vs. T.Hawk: Tomahawk Buster (usually loses so there's no point)
Vs. Fei-Long: Flame Kick, Chicken Kick, Super
Vs. Cammy: Cannon Spike, Spin Knuckle, Super
Vs. DeeJay: Machine Gun, Short Jackknife (don't let him get a read on you)
Vs. Boxer: Super (DP loses to Buffalo Headbutt but it can take out Crazy Buffalo)
Vs. Claw: Scarlet Terror
Vs. Sagat: Tiger Uppercut (don't safe jump vs. Sagat LOL)
Vs. Blanka: if you jump in with a punch at a range that would stop Vertical Balls you can add a built-in fireball or super fireball to defeat wake-up Back Hop attempts.
Once you get the hang of this technique it's just a matter of coming up with your own preferred setups. Against Honda I find that doing it with jump kick -> low roundhouse -> fierce fireball feels nice. If the built-in DP hits that's fine, if the jump-in -> low roundhouse hits that's fine and if the whole thing is blocked you press the advantage. Consider Aniken's setup:
jump short (built-in DP) -> crouching medium punch -> low roundhouse (-> fireball)
If this hits, his opponent is knocked down and near dizzy. It's also easy to hit confirm, and Ken can lock down with the fireball or stop at the low strong and look for a knee bash mixup. That makes it an extremely well rounded sequence.
This type of option select can be done with any attack including a normal move. For example, you can use a crouching uppercut to stop Ryu's Hurricane Kick. Time it properly [on the slow side] and then if Ryu blocks your jump-in you get nothing, if he does a wake-up HK you'll beat it with the built-in punch and if he does a wake-up DP you'll land and block it. When I saw Shiki playing Boxer at Star Cup he was doing this well.
[NH2 says: you can mess with this on an emulator. Get a MAME cheat file and turn on the easy special move cheat for 2P's (would-be) wake-up special move. Then assign 1P's jump kick and 2P's special move all to the same button. Now if you do a deep jump kick with a built-in Dragon Punch you can see how the trick works. The timing isn't exactly the same — this will only work against slower wake-up attacks.]