Hi Simeon!
I personally use that time to write little things that aren't needed but would be usefull like my ftp remote-editing script. I also spend time then to read/browse things like Perl Paraphernalia, YAPC talks, WT Columns by Randal/merlyn or The Conway Channel: Diary for example.
Of course there's lots of stuff to read/learn here at perlmonks, too.

Besides of that I also love it to simply do "nothing". Refresh your brain, relax, concentrate on your breath and think about non-thinking. I think it's very important to have those timeouts during the day to get new inspiration etc. It will get a true source of new ideas one you get used to it.

giant