The only thing I've done with them is that I put big plastic bows on them and pile them in a Santa wagon I put on my front patio at Christmas. They look like Christmas gifts and don't get messed up in the wind, rain or snow at Christmas. Mine are big tins (like the ones pre-popped popcorn comes in.

Oh, I've also seen where people cut them up with tin snips and use the colorful pieces to cover things like a photo frame or the frame of a mirror or bulletin board. Be careful, of course, because the edges are really sharp when you cut them up. Here's a link that shows a pic of what I mean:

http://recycledcrafts.craftgossip.com/files/2009/03/pop-art.jpg

Here's a couple of other links I found while looking for the one above. While they're more for using soda cans, I thought they were kind of fun to share:

http://www.make-stuff.com/recycling/

http://recycledcancrafts.blogspot.com/

http://gingerbreadsnowflakes.com/node/163

I received one as a gift last Christmas. It had been planted with tulip bulbs that were forced and it was a beautiful breath of spring in the middle of winter. It was my favorite gift last year. I plan to get some bulbs this fall and forcing them in the tin for this winter.

Not completely an outdoor idea, but I melted down a lot of Christmas candles that had been poorly stored in the attic and were disfigured and poured them into the tins with 3 or 4 wicks in each (cookie size tins). We take them camping because the lids keep everything neat.

Pam

put some flowers in them, then stack them up like a tier. use some empty ones to stack them on ,or use bricks. if you have a LOT of them, make it tiered on 2 sides, or all 4 sides. it will look like a fountain of flowers.
you might want to use some disposable diapers cut up in the bottom, they really hold moisture so you don't have to water as often in case some of the tins are shallow. wet the diaper pieces first.
you could use a tin on your mailbox, if you live where you have a mailbox, lol! use a larger one, nail it to the post, and plant. maybe paint it a nice color.
make a tin man :D

great ideas. i love the tulips planted. wish i could have tulips without so much work!
i may have to try the candle idea for my back deck and front porch!

kudzu

Here is a link that might be useful: Kudzu's Blog