We usually use some of it for personal purchases/extravagances. We don't set a specific amount, but I'm the one who budgets, and if I want something and I think we can afford it, I talk to dh, then get it. Most of it goes to our car insurance.
This year? Not so much. Since Christmas, we've:
1) Bought a new computer. My in-laws put a big chunk towards it as our Christmas present, but there was still some out-of-pocket. DH needed it, though. He's in IT, and works from home sometimes (esp. when he gets a page), and our old one just wasn't fast enough.
2) Bought a new minivan. We have monthly payments to make, and it's a much newer van than our old one, so our insurance will be somewhat higher this year.
3) Had to pay for physiotherapy (physical therpay in the US) for my back and ds1's knee. DS1 also needed a $150.00 brace. We can get most of that back through dh's extended health coverage, but we have to eat some of it - and I lost the receipt for the brace.
4) DS1 was in the Provincial Gymnastics finals. That cost us $350.00, for his registration and travel expenses.
5) We've had to make the last two payments on ds1's choir trip in April.
So, yeah...new computer, new van, medical costs and extracurriculars have dogpiled us the in last three months. If dh does get a tax refund (not sure yet - he switched jobs twice last year, and I'm not sure what the overall picture is going to be), we'll be lucky if it covers the car insurance. If there's anything left over, it goes to the Visa. Our overall financial situation is good, but our current cash flow is a bit...slow.