Expiring xbox points

I haven't used my xbox 360 in a few months (checking recent transactions suggests the last thing I did was play Brothers on it, so Augustish?) and today discovered that 500 points expired. I'm not entirely sure why this would happen and pretty sure I wasn't given any warning.

Anyway, I've still got about 3500 points on that account (I bought point cards on sale last year assuming that something in the Summer of Arcade would catch my eye but nothing seemed worth it). I'm assuming the best thing to do would be to spend it all before it randomly expires so would love some tips on what to get. I've generally bought & played all the more prominent titles that came to XBLA so smaller / indie game suggestions would be appreciated. Thanks!

All those MS points should have been converted into Xbox Bucks.

thanks for the replies but nope, I've got an email saying they'll convert to real people money in March. I've still got regular points according to the website.

My concern was that more points will expire before that happens leaving me with way less money than I think I'm owed.