I've been working on JStreamer (including the extremely crude prototype that preceded it) for about 6 months, and at last it's available as a beta release! I'm excited about this because it's the first software offering that's truly "mine" in the sense that I designed and developed it myself and I'm also the legal owner of the code.
The other thing that I've found exciting is that JStreamer has turned out really well. Most software has inevitable compromises with some parts having functional limitations or design trade-offs, or not being as easy to use as it ideally should be. To my great surprise, this hasn't happened with JStreamer. So far I have been able to add functionality and remove limitations with clean designs and no compromises, and there have been a number of "Yes it can" moments. Of course the real test will come when users try to do things that I haven't anticipated, and we'll see how well the design holds up then!