The main coping tools are probably exactly the same as they are for anybody else, actually - just the stakes are higher for those with ADHD!

- Proper sleep. Probably the biggest single factor. I don't always excel at this. When I don't get enough sleep nearly everything else is moot.

- Proper environment. The exact definition of "proper" will be quite different for everybody, of course. Pay attention to what works, and don't be afraid to suggest alternate arrangements to your manager. You don't have to mention ADHD ever - just mention the facts ("I'm having a tough time focusing in the noisy part of the office") and provide a constructive suggestion ("Is it okay if I work alone in the unused meeting room when the noise at my desk is too distracting?")

- Proper diet. Another thing I'm not great at. But foods that cause sugar spikes and crashes make it hard to focus for anybody, especially me.

- Exercise. Really, really helps. (True for anybody, of course!)

- Lists. The key, as I learned from Getting Things Done, is that no task should be more than 10-15 minutes. If so it should be broken down into smaller tasks. Additionally, you must review/prune your list regularly so it doesn't turn into a big failure/guilt pile.

- Medication. It helps. For me it's only maybe 25% of the puzzle or so and can be rendered moot if I'm in a distracting environment or am running on no sleep.

Medication is one tool. (This includes other stimulants such as caffeine which some ADHD people self-medicate with.) No tool is sufficient in isolation, though - different people need different sets of tools. Here's a book I've found helpful in presenting a bunch of different tools: http://www.amazon.com/gp/product/0415815894

Social support, using todo lists, lots and lots of effort to establish habits, so you can stop spending so much daily effort (CPU) on things that most people can handle with GPU.

In addition to medication, like mkopinsky said, I've had great success keeping a Bullet Journal[0]. It keeps me on track day to day, but medication keeps me on track minute to minute. I definitely spent a lot of time in college (years before I was diagnosed) trying different productivity methods and tools, but nothing would stick past a week.

[0]: http://bulletjournal.com/