Well, nails take a while to grow and they actually grow slower in the winter. So itll probably take time, no matter what you do. But they definitely will look better if you follow a few simple things. Here are some links to help. The first one is really fabulous.

http://donkel.wrytestuff.com/swa59786.htm

http://www.naildoctors.com/nail_info.htm

Okay, so if you want to just get them to look nice while they're growing and if you're dressing up or something, you can always try fake nails. They can look quite nice and you can get really cute designs, but I don't know if they're really good for your natural nails

i had exactly the some problem for YEARS! my nails are extremely flimsy so this should probably work for anyone, for me i took a day , filed and cleaned what i could and clear coated them, i clear coated them until it layered then took off the nail polish and did it again, you can also get a nail strengthener, it's like a a really thin clear coat in a pen you put all over your nail, it really helps. when they start growing and getting longer. remember DO NOT PICK! and if you play any sports either on your own, on a school team, on an organized team ANYWHERE just be really careful with your nails. i snapped off half a nail in basketball practice once!
hope that helps :)

Use a good nail strengthener, remember not to use your nails as tools!
My nails always grow a lot faster when I have nail polish on, because I don't like to mess my nail polish up so I treat my nails more gently.
Try your hardest not to pick your nail polish off! Picking nail polish off strips the nail of stuff that it needs to stay healthy and strong, and makes them thin and weak.

I had the same problem as you until I found Claire Topper Naillure nail Strenghtener. It is the most wonderful stuff in the world. It is blue in color, paints on, dries in, and never know it on there, It makes your nails so strong. Now I can't it anywhere. Maybe both of us looking for it we can find it. it u do let me know. kats_shelties@yahoo.com kathy