I know you're not asking me, so I'm going to give some totally unsolicited advice (which everyone knows is the best kind).
Ship something. Either commit to someone that matters that you will finish something useful to them (e.g. a client, a partner, a spouse, etc.), or commit to releasing something to the general public (e.g. an open source project), or commit to showing off something you built at a democamp or conference.
Like you, I am interested in many different areas. I also tend to start a lot of projects that I never finish. However, because I am a web developer by trade, I also have a lot of projects that I must finish, and many times it is the last, difficult, 20% of a project where I gain the most understanding and knowledge.
To truly grow you have to commit to do something hard and then you have to follow through on it. There is no substitute for that. The great thing about being interested in computers and programming (because of this forum I assume you are) is that it is very easy to combine multiple interests into single projects. If you are interested in biology and robotics, for example, it will not be difficult to conceive of a programming project that includes both.
Good luck. I look forward to hearing about your launch.