A Reston Kid has a nice collection of math blogs to start with, all people who are on the mathteachers twitter list.
For example, Jim Knight tweeted: 35 web 2.0 educational resources. Some are no brainers, some charge, but I found several new ones of use to me.
Kate Nowak tweeted the MathFail website where the image at the bottom came from.
Reston Kid (blog link) also tweeted out Frink, a "practical calculating tool and programming language designed to make physical calculations simple." As RK notes, the documentation is hilarious.
EDIT: Cathy Campbell (@ccampbel14) points out this great post on Twitter for math teachers.
The first Math and Multimedia Carnival post is up at Guillermo Bautista's blog. Lots of interesting stuff. Sol Lederman's puzzles, Maria Drojkova's educational twitter uses, David Wees building off Dan Meyer's video problems and more.
For example, an Alexander Bogomolny post at C(ut)T(he)K(not) Insights, who's hosting the next Math Teachers at Play. I'm excited as his Cut-the-Knot (a Gordian reference?) was one of the first worthwhile math sites on the internet. (IMHO)
Of course, if you're on vacation, more power to you. Maybe you'd be interested in trying our new family game... C'mon, please?