Rare day

It's a rare day indeed in this household when a financial surprise is a good one. Today was one of those rare days. My daughter checked the mail after I arrived home from work and handed me an envelope marked from the child support agency. I pay child support for my son, Book. I used to receive child support for my son, Pooh, but he's 21 now, so that stopped long ago. I had a debit card for Pooh's support, onto which the state deposited my payment each week. I had a total of $4.77 left on it when Pooh turned 18, which I just never ended up using because, you know, it's a debit card, and it was $4.77. I never felt comfortable saying, "Here, use $4.77 on this card and then I'll pay some other way for the rest of the cost." So I just left it sit there. Apparently, that card has expired, or was due to expire soon, because I received a replacement in the mail today. I remembered, "Oh yeah, it had a couple of bucks on it so they sent a new card. Oops." I called and activated it like a good girl, and after I selected my PIN, the automated system told me my balance - nearly $1,300! What?! Well, I logged into the account online and discovered that my payments did not stop in May of 2009, when my son graduated high school. They continued on through the end of the year, during the summer and then while he was enrolled full-time in college. He left after the first quarter. I'd be rolling if he hadn't, because apparently the payments would have continued as long as he continued, uninterrupted, as a full-time college student. I suppose it can be forgiven that I was entirely unaware of this fact. I never opted in for any type of notification on the account, because the debit card was a brand-new thing just before he graduated. Until then, I'd been getting checks. I also had another excuse - I was completely useless for about three months after his graduation day because it was on that day that I was unceremoniously and without warning dumped - via text message - by the love of my life. It made for some entertaining blog reading for him and his new girlfriend for a while. Now, I've got this money I didn't know I had which has been languishing in a non-interest-bearing account for three years. What to do with it?