That's a good idea, Kriston -- ds6 loves math games. They're learning ordered pairs at school and they sent home a "game" to play -- a big 6x6 line grid. We rolled the dice and used the numbers as our ordered pair, and graphed it. First player with three dots in a row won.
It really nailed the idea home, and ds loved it -- even though I won both times we played.
Games like that can be really mathy, and really fun. We just got a dice game at Barnes and Noble that included two 12-sided dice and three regular six-sided dice. You roll the 12 sided dice and multiply to get a "target number." Then you roll the 3 regular dice and try to get as close to the target number as you can with those numbers, using addition, subtraction, multiplication, division, exponents, etc. It's a lot of fun; ds really likes it.
So that lengthy intro was to say I agree! There are lots of fun ways to afterschool without making it a chore.
Another option is to work the afterschooling into your nightly schedule -- 15-20 minutes after dinner/bath is really all it takes to spread those little minds. We've taken to doing ds6's homework and playing a mathy game (Yahtzee or a "tricky math" worksheet or Timez Attack) between shower and bedtime, and it's working out nicely for us.