If you submit your idea to PADB your idea will be publicized. In theory that means that the idea cannot be patented. In practice it means that you can invalidate any patents that happens to be based on your idea if you can document that your idea predates the patent.
PADB is using ToPAS to secure that the ideas are timestamped in a way that will hold up in court.
There are a few arguments against using PADB. The arguments will currently only be valid for a few.
To submit your idea you will have to write your idea in a file and add it to PADB using CVS. If you do not have access to CVS you can simply mail the ideas to a human that has access to CVS.