[Before I start, let me admit that I am still very much a programming n00b. Everything that excites me is probably old hat to the majority of the coding population.]
I like tags very much. They are a million times better than folders. 'nuff said.
I've been writing a tagging system. It's nothing special -- just something that pairs up items and tags, and can do some of the same kinds of lookup that the tagging systems on blogs can do. Have been wanting to do this for quite some time, so now I feel all accomplished :D
I haven't finished testing the thing yet, so there are probably a lot more mistakes hiding in there, but most of the ones I've caught so far have been pretty similar. I tend to confuse the actual tag object with the tag's name, and refer to one when I should refer to the other -- kinda like confusing the phrase "scientists are people too" with the tool that lets you do this. Same thing with confusing tagged items and the objects they contain. These are pretty easy to fix.
There are a couple more functions I want to write -- eg, I haven't got a thing that lets you organize the tags in order of frequency of usage (as they are in the sidebar). But I've got the majority of what I wanted. (And no, that doesn't include a GUI. This is strictly text-based, Python-command-line stuff.)
I guess I'm kind of excited because, back when I was thinking about teaching myself to program again, a tagging system seemed like kind of a big challenge -- one I could do relatively quickly, but a challenge nonetheless. And now I'm about 90% of the way there. It's astonishing how fast you can learn to program when you've already learned to program twice before! ^^
This is also the longest block of sitting-and-writing-code time that I've spent in quite a while. I seemed to fall into a sort of trance -- very focused, very losing-track-of-time. This is an interesting mindstate (not to mention a very productive one!), and I'd like to get into it more often. (It helped that some people over on the XKCD forum turned me on to the streaming lyricless music from Blue Mars, which bills itself as "music for space travelers". Despite the word "mars" in their title, I think they really mean "music for headspace travelers". I find it quite relaxing and focusing.)