Way to wait til the last minute, dumbass.
Sorry.
I've BTDT plenty of times too.
Now, for all you students of marriage, find a woman who makes cakes. Especially wedding cakes.
She will usually do them for very cheap. ($20 is average).
I got my wife an 8 inch circular layered cake for her birthday last month.
All I told the lady was "make it really nice, with flowers or something"
She made a cake that impressed even an emotionless prick like myself.
It looked like a woven basket on the sides, and was covered on top with huge flowers.
My wife liked the cake more than her birthday present, which cost a lot more than the cake.
Another time this worked well was our 1st anniversary. We had our cake top from the wedding, and were planning to put it in the freezer, but left for our honeymoon, and left it on the counter. So I had a picture from the wedding, and gave it to the cake lady. She made one exactly like our original. My wife was actually crying when she saw it.
Now, BeetleBailey, since you are short on time, stop at Meijer, or Kroger, or a Bakery, and see if they can't whip something up by tonight, with just some words on top. It will work almost as well. A Dairy Queen frozen cake could work too.
Then, pick up some flowers (my wife likes carnations better than roses, and they are cheaper than roses, too) and pick up some massage oil and a card. Tell her you are devoting the entire evening to her. Make her dinner. Do the dishes. Give her a massage, etc...
This will mean more to her than any expensive gift.
You can thank me tomorrow.