What are your (successful) strategies for finding (side) projects you're truly passionate about?
1. Leave the house. Take a walk in an unfamiliar environment.
2. Clear your head. This might take an hour of steady walking.
3. Ask yourself what problem exists, that you know about, that you understand, that can potentially be solved with a computer, that is within reach but remains unsolved.
For example, my most recent side project was a way to put all my books into a database by using an Android bar code scanner, something that didn't exist the last time I thought about this problem. I hadn't thought about it for a few years, then recently I decided to revisit this issue and see if anything had changed.
It turned out that everything had changed -- Android devices are cheap, they can scan bar codes, new books all have bar codes -- it was a "duh" moment.
Here's the result -- my free book scanner project: http://arachnoid.com/LibraryDB
Basically, you need to think of a way to temporarily disconnect from your environment, give yourself a way to think about programming issues from a new perspective.