I have had tons of fun dinking around with these 23 Things this summer. This term in school I'm taking LIS 768 Library 2.0 at St Kate's, taught by Michael Stephens (the dude who writes the Tame the Web blog, among other things). This was our first weekend, and boy, am I glad I'd done the 23 Things! It all made sense to me, and it was much more enjoyable to be able to further refine my knowledge.
As for staying current, no problem. There are some Things that I probably won't ever use, others that I'm not ready to use yet, and some that I have embraced wholeheartedly! I plan on using some of these Things to build a web presence for the Winsted Library. I've learned more about Web/Library 2.0 things so far this year than I ever thought I would...and better yet, I have fun seeing what the different things can do.