I work at JoAnns and we get people in wanting ideas that are cheap and easy to do. Alot of them have already been listed here!
There is also a book you can find by Wilton's and it has TONS of ideas in it. Or you could visit their website at:
http://www.wilton.com/ if you are still deciding. The book has things for different times of the year. Just a thought!
Good luck and congrats!