Update: Looks like this offer was reactivated and is good at least until Tuesday night (technically 1 a.m. eastern time Wednesday or so).
You pay $10 to get a $20 voucher for Toys R Us. Note that the voucher expires Dec. 24, 2012, can only be used on purchases of $20 or more, and is only good in store, not online. So don't buy it if you're not sure you'll be going to a Toys R Us store to buy $20 of Transformers before Christmas. As usual it can't be used with other "total purchase discounts" (like a 20% off coupon or something).
Full disclosure: I believe the link below has a referral code for me in it, which means I might get credit if this is the first groupon you've bought. If you don't want to give me credit just get rid of the referral code. I'm putting this up for your benefit, not to rack up groupon points.http://www.groupon.com/deals/dc-gxb-toys-r-us-november?utm_campaign=UserReferral_dp&utm_medium=email&utm_source=uu14078341
Want: Universe Jetfire.
Have: Too many to list.