If you’re happy just using open source, then no problem. But if you want to contribute, because you have a problem that nobody else is fixing — or simply because you want to do your bit in exchange — it can be difficult to know where to start. The following suggestions might just inspire you to join in.
Then this post goes on to give some suggestions. Most important two: use OpenSource software, and note that you don’t need to run Linux to use OpenSource software … there is lots available for the Mac and that other system as well.