If you have one of those All-Glass Aquarium brand mini tanks, and you want to grow plants. I'd recommend replacing the incandecent light bulb with one of those screw in mini compact flouresent bulbs.
If you add the plants and fertilizer, you may not need to "cycle" the tank, especially if you have other tanks around. If the plants are growing they will easily consume all the amonia produced from a couple tiny shrimp. However you can place a cup of gravel or a dirty filter cartridge from an estabolished tank inside the mini tank for a couple weeks to "jump start" the cycle, as a back up to your plants, just incase they don't grow well at first.
With the plants you really won't need a filter, except you'll probably want something to gently move the surface of the water to prevent a nasty scum from growing and floating at the surface. On of those tiny hang in tank filters tank come with the mini tanks would be fine for this. As long as the water is clear you wouldn't even need a filter cartridge in it.
For the mini tanks, you will want very small plants or very slow growing plants so that they don't quickly out grow the tank, unless you have another tank to transfer them to when they outgrow the mini tank or you want to chop it off at the water level.
I've had a plant only tank in one of the 2.5 Gal All-Glass Aquariums set up and going for about 8 months now. I don't maintain it nearly as much as I should (it could look much better). I haven't even changed the water in it in a couple months, and the plants are still alive.
Karen Randall has a good article on mini tanks here is a link:
http://www.aquariumfish.com/aquariumfish/detail.aspx?aid=480&cid=58&search=
