At work, I've been taking a bunch of CGI scripts I wrote, and making them use template files for the HTML that they generate.
A typical build-or-reuse situation; in this case, I'm building because the need is short term (my client might hook a big investor if I can get this thing running soon enough) and the requirements are so simple. In the long run, it'd probably be better to spend the time investigating something like PHP or Perl::Mason or some such, but I'm in a hurry, so I just whip out pattern 20.9 from the Perl Cookbook.
On another front, I put a little more time in on my (eventually to be) open source project last night. I'm using FLTK, mostly just to learn about it, and because I will want to be able to run it under both Windows and Linux eventually. In a typical cross-platform quandry, I'm trying to decide how much effort to put into Windows specific code, things like making it display different task bar icons when the program's in different states.
A bit of personal cross-platform history: my first cross-platform code was written using a commercial library called XVT, which at the time supported Windows 2.0, MacOS, OS/2, and Motif. I was amazed to find that it's still available.