On projects that don't die
I find it interesting to track which of the things I create that continue to exist and flourish when I get bored with them, and which just drop dead when I stop working on them, and everything in between.
For example, I've posted several times before about random people still do with my obsolete-before-I-even-wrote-it Linux Arcnet driver.
Another one that I find interesting is the Debian Popularity Contest, which I created in... hmm, late 1998, almost ten years ago now. I intended it as a simple way to demonstrate that Debian really didn't need to distribute a 5-CD set; the packages most people wanted would happily fit onto one CD. Also, I was hoping I could forge enough results to get joe installed by default.
The first goal worked out great; Debian and Ubuntu now use popcon to fill their CDs, and your system will be just fine even if you only download a single CD image. The second goal unfortunately still hasn't come to pass... perhaps someday.
But more interesting is where these projects went beyond my original intention. The reason arcnet is still popular is that it's used in quite a few factories, because of its extremely good noise resistance and because it's good enough that nobody wants to replace it.
And popcon? Well, it now seems to have become the de-facto method of resolving things like vi vs. emacs wars or how soon git will be more popular than cvs, including a graph all the way back to 2004.
Update 2010/01/04: Thanks to Richard Soderberg for an updated link to the popularity-contest chart. He also pointed out that git-core now is more popular than cvs; it happened on 2009-03-21. At the current trend, it looks like git will overtake svn in another year or so.