Having Lots of Ideas; Work on All or Few and How to Know?

Focus. You can't know if you have a winner or a loser until you've been all-in on it for a little while.

Pick the one you can stand to spend every working hour on for a few years (assuming it proves a workable idea, and you see a path forward at each milestone you reach along the way), and forget about everything else.

Every nerd has a lot of ideas. You are not unique. The difference between you and the ones who succeed is that they commit to something and go all-in. They may have to do it a half dozen times, or maybe the first one will be the winner. Doesn't matter. Until you focus on something, you probably won't make something great.

Pick several metrics that are relevant to you (such as market size, revenue potential, chance of completing the project (and time it will take to complete), how interesting the work is, confidence in how good the idea is). Use each metric as an axis of a graph (it could be multidimensional) and then place each idea you have on that graph.

For inspiration look at the BCG matrix: http://en.wikipedia.org/wiki/Growth-share_matrix

It's a tough decision. You should not ignore where your passions lie, however as has been suggested elsewhere if you want this to be your core revenue stream you must understand the relevant metrics.

I've written about this on my blog, where I have discussed this and similar topics in greater depth: http://www.fourthirds.com/which-idea-to-bet-on/.

You might also be interested in reading Seth Godin's short book The Dip. This discusses ways in which you can decide when enough is enough.

I'm always happy to be a sounding board, in as confidential a manner as you wish, for ideas and offer advice on what to do next. Hit me up at the blog if you want to take the convo further.

Good luck!

Pick the project closest related to your hobbies

If they are all as equal as you claim roll for it. I suggest the d12. It is highly underutilized.

> at what point should you realize that you should move on to something else

When you or your trusted partner(s) no longer believe in it. (the trusted partner is needed because most everyone is susceptible to being blinded. Between the lot of you hopefully one can see the truth.)