I have short nails, and these are some of my past designs.
I've had a design once where I did a different smiley-face for every single nail. My thumb would have a frown, my index would have a smiley face with a tongue sticking out, my middle finger would have a wink, and so on forth.
Another design I had was where I spelled my name out on each hand. Since my name is five letters long, it worked for me. My thumb was J, my index was A, my middle finger was I, and so on forth, haha. You don't necessarily have to use your name, just find a five letter word and it can look really cute.
Oh yeah, my friend has domo-nails. They're really cute.
http://fc09.deviantart.net/fs70/f/2010/107/e/4/Domo_Kun_Nails_by_ElineInWonderland.jpg
I just got that from the internet, but my friend has that same design. :)
You can also just paint your nails a solid color and add a little floral effect in the corner. Here's an example, but it's with spider-webs.
http://i.ehow.com/images/a05/ac/22/create-spiderweb-nail-designs-halloween-200X200.jpg
Hope this helps. ^___^.