I thought I would share a few cheap decorating ideas that I used on my tank. I'm a college student on a budget, so I like cheap

I used poster board, glass clings, and duct tape. To make a cheap tank cover you need some kind of mesh (I used an old window screen) and duct tape.
You can get glass clings that look like just about anything, they even sell ones that look like stained glass online. I've even seen some cute ones that look like dragonflies at Walmart! I picked up holiday glass clings for a dollar, so now I have Halloween bats on my tank
I also used a piece of neon poster board (the small, thin kind used to make signs) for the back of my tank. Poster board comes in a wide variety of colors, and sometimes it comes in multi-packs of several different colors for really cheap! Just cut it to size and you're ready to go!

You could even decorate the posterboard yourself if you want to! I used something similar to this
http://catalog.teachingsupplystore.c...-p-131561.html
Duct tape comes in all kinds of patterns and colors, and I used TINY pieces to attach the poster board on the back of my tank. I also used it to make my tank cover.
For my tank cover, I took a piece of old metal window screening and cut it to fit the top of my tank. Then I wrapped the edges in colorful duct tape to keep the screen from unraveling. I use poster putty to attach the cover to the top of my tank so that my fish can't jump out. It looks cute with the matching tape, and it keeps my fish safe!
You can definitely do a lot more than what I did with the decorations I used, so I hope I gave someone an idea to go rummaging through their house and get creative!