I've never been able to find a decent magnetic chess board. At least, the tiny travel ones are always a bit rubbish. Turns out if you're willing to put your crafting skills to work, you can fashion your own, full-sized portable board from paper.
Instructables user "belsey" has put together some great templates as well as tutorial videos that provide you with everything you need to make your own. The template for the board and pieces normally goes for $US3.95, however, if you use the code
INSTRUCTABLES at checkout, you'll receive a 100% discount (free, in other words). This code will however expire after 500 uses.
One of the niftier points of the design is that the pieces slot into each square, so it'll take fair whack to ruin your game and makes it great for long car trips (at least for those not in the driver's seat).
Not a bad project for the weekend!
Pop-up Paper Chess Set [Instructables]