The "mind dump" is a way of getting a lot of information out of your head and into your organisational system. It's a simple process that doesn't take particularly long, although it may take longer if you haven't done it for a while. It's a great way of clearing your mind, and it allows you to get a good view of your projects, commitments and tasks.
A good time to perform a mind dump is at the end of every week, just before your weekly review. Another good time to use it is when you're feeling overwhelmed with work, or when your brain is swimming with ideas and you can't concentrate.
Make sure you have at least twenty minutes of uninterrupted time, sit down and relax. Take a sheet of paper and write down a task you want to do. This can be something simple like making a phone call, to something larger like setting up a blog or starting a business. Absolutely anything goes, so write as much as you can. I generally write down at least a hundred items if I haven't done it for a while, but you may find you only write down fifty. The important thing is to get as much out of your head as possible.
You can either write every item on a separate sheet of paper, or write them all on to the same sheet. I prefer to write it all on one long list, but you may find separate sheets are easier to process.
This all depends on your organisational system, but a rough GTD method is as follows:
Go through each item on the list. If it's something that will require more than one task to complete, it's a project so it gets added to a "projects" list. If it's a single action that will take less than two minutes to complete, do it immediately. If not, add it to the appropriate "to-do" list.
If it's something you want to do, but don't know when (such as taking a holiday), write it on your "Someday/maybe" list. As soon as you process each item, cross it off the list or dispose of the sheet it was written on.
The main benefit of this technique is that it gives you a clear mind and helps you concentrate. Once you've processed the list, you know everything you were thinking of will be taken care of, and your mind can rest at ease.