I can give my method I used to control my anger. Not sure if it will work for others since I now have a new theory about its interaction with aspergers and ADHD, but it might help.
To start with when you start getting angry, recognize and memorize the feeling. Learn it and whenever you feel it spark, clamp down and try to clear your head before it can grow any further. Anger feeds itself, the more you let it go the larger it gets and the more it muddles your higher thought processes(in essence, anger makes you stupid). It helps to think about it and ask yourself the question "What will getting angry and losing my temper accomplish for me at this time?" and you'll quickly come to realize that the answer is probably nothing. Outside of combat, shady negotiations, and other things of that nature, anger is unhelpful at best and actively harmful at the worst to you, the people around you, and the situation you're in at the time.
Think the situation through in your head and think about where it will go once you get angry and I doubt it will be anywhere good if thought about with a clear head. This is exceptionally easy when online as you can type up your response, then re-read it, take a break to calm down, re-re-read it and if it's pointless inflammatory raging that would feel good at the time but you will regret later, just delete it before posting it. If this process takes 30 minutes, no big deal because you can afford the time. Less useful in active chatting like IRC but even then 5-10 minutes to respond to a post isn't out of line because sometimes RL calls and that can be all it takes to see and delete a stupid post before you hit enter.
Yes, going as far as I did where it's VERY difficult to even feel it probably isn't the healthiest way to go about it but having control will help and coming to not only recognize but fully internalize it deep into your subconscious that getting angry is just not worth the problems it causes most of the time helps to control it because you begin to see that it really never helps. After some time you'll stop your anger from flaring right as it sparks as a reflex rather than a conscious action after you feel it begin burning.
It's not as easy as it sounds and is definitely not quick, but it allowed me to contain and control a rather volatile and explosive temper without any medicines or drugs. In fact I started doing that specifically to AVOID having to rely on drugs because I hated the side effects(and sometimes the primary effects) and while the rest of my family practically has to pour milk over their morning meds and eat them like cereal to resolve their various issues, I don't have a single prescription to my name despite having most of the same problems and I am one of the most stable in my family because I don't rely on drugs that can lose effectiveness or wear out and instead used raw will and stubbornness to get the same result.
Not to say I don't have my own issues and my social skills aren't helped because I have a time delay on my brain->mouth process to prevent myself from saying stupid shit as well as preventing flares of anger from leaking out, which also tends to be stupid shit, but it did help me control my anger and that's the focus of the issue right now.
Ok, that rambled on alot more than I expected it to and was heavily stream of consciousness but that is how I did it. It's not quite meditation since having a clear head in general isn't the method or goal, it's clearing away the sparks of anger, hate, depression, ect as they are forming but before they can grow to consume your rational thoughts that is the goal. A clear mind is really a side effect so there's no sitting in quiet contemplation and more watching your emotions and preventing flares of the unwanted ones until it becomes an automatic reflex.
