While the holidays are behind us, hopefully you're still holding on to your bonus if you received one. I know that many companies don't give bonuses until February or March, so if you work for one of them then you have some time to decide your bonus's destiny.
Many companies give the option of directing a percentage of your bonus into your 401(k). It's a great option because that money skips your bank account and heads straight for your retirement account. In the past, I've used part of my bonus to pay off any lingering credit card debt which should be high on your list of priorities.
I'm sure what I'm about to say would enrage some really serious savers, but I think it's okay to treat yourself to something with a designated amount from your bonus after you've taken care of the items mentioned above. Think of it like a little allowance to buy yourself something fab that you've had your eye on for awhile, or maybe put some of your bonus towards a vacation fund. As long as you're financially healthy, why not live a little? Just make sure you don't spend your bonus before it's given to you.