First, we have a floppy disk plant holder that is simply made by making a box with the floppy disks and a plastic container to hold soil and water. The nice thing is once the plant dies, you can easily transform this box into a storage item that could hold spare change, pens, or other odds and ends.
Another idea is using cardboard coffee sleeves, which we have plenty of here at the store. This is a project that needs no glue or tape, just simple folding. For the directions, click here. These obviously will not be able to stand for a long period of time for their own, but they are perfect to give as a gift.
Finally, you can plant your seedlings in these old book planters. For inspiration, you can look at the number of examples they have on digsdigs.com. These planters could be made out of hard cover books, magazines, phone books, or old paperback books.
If you are a little bit more ambitious and want to make sure you are ready to garden when the weather is right, you can make your own gardening gear out of PVC pipes. You can create your own strawberry tower or even your own PVC garden trowel.