The following is the description of a low-cost 5 gallon nano reef which can be easily set up and successfully maintained by just about anyone. There are many other ways, of course, to set up a similiar tank, and I do not claim that this way is the "best". It does, however, offer the advantages of being both cheap and simple. Further, if the simple maintainance described herein is followed, the tank should be quite successful.

When I get a few minutes, I'll put details on similiar 10, 15 and 20 gallon setups.
 

SUPPLIES:
5.5 gallon All-Glass Aquarium ($5-$10)

cover glass for same ($5)

Skilter 250 ($25 mail order, $50 at most pet shops)

Custom SeaLife's SeaLights Power Compacts Fixture (27w "daylight", 9 watt "blue") (around $75)

50 watt heater ($15)

hydrometer ($12)

thermometer ($2)

5-10 lbs of good Fiji live rock or Tonga Branch Rock (well cured, if possible) (varies)

5-10 lbs of live sand (varies)
 

Getting the best quality live rock possible is very important. Since the quantity of rock is so small, buying the higher priced rock should not present much of a problem. If at all possible, use cured live rock. It is possible to use uncured rock, but cured rock is easier, cleaner and allows you to add animals much more quickly.
 

The use of live sand is optional. If you choose not to use it, go with a bare bottom instead. Again, because the quantity needed is so small the cost of live sand shouldn't be much of a factor.
 

Set up the tank by filling it with water. Many pet shops now sell pre-mixed salt water made with Reverse-Osmosis fresh water. If you have a nearby pet shop that offers this service, take advantage of it. If not, you'll need to mix your own salt water. If your tapwater is full of phosphates, nitrates or heavy metals it will need to be filtered with either an R/O unit or a DI filter before it can be used in the tank. Remember not to fill the tank all the way at this point, as the rock and sand will displace a considerable volume of water. Add your heater and bring the tank temperature to around 78 degrees before progressing any further.
 

Put your sand into a plastic sandwich bag (sealed). Holding the bag under water near the bottom of the tank, cut off a corner of the bag and slowly pour out the sand. This will prevent the worst of the tank clouding that can happen when using sand. Next add the rock and arrange it to your satisfaction. Try to leave as much of the sand uncovered by the rock as possible.
 

Connect up your Skilter 250. Open the skimmer "full throttle" and let it run. Depending on how cured your rock is, you will need to let it sit in your tank on it's own for some time. If you don't have access to test kits to monitor the condition of your water, you should play it safe and leave your tank empty for about a month. During this period you should leave the lights off and the skimmer on.
 

When the rock has fully cured, the first additions to your tank should be various scavengers and algae eaters, namely hermit crabs and astrea or turbo snails. Approximately 1 turbo snail, 3 astrea snails and 6 blue leg hermits should do a good job of keeping the tank algae free. Also at this point you should begin turning on your lights -- a photoperiod of 10-12 hours a day is good, and a cheap appliance timer can automate the process for only a few dollars. Once the rock has cured the need to run the skimmer full time is obviated, and you can begin closing the throttle on the skilter whenever. Allow it to run at least a few hours a week, more if you wish.
 

Before adding other creatures it's a good idea to perform a heavy water change at this point, especially if your rock experienced a lot of die off. Replace about 50% of the tank water with new salt water.
 

Good corals for this setup include mushrooms, leathers and most soft corals. Certain hard corals can also be kept, although you should only consider relatively low-light species. A cleaner shrimp or very small fish can round out the tank. A clownfish/anemone set up can also be kept, consisting of one small anemone and one small clownfish. In such a small tank I wouldn't keep any other invertebrates, as the anemone could cause big problems by wandering into the other inhabitants.
 

Add your inhabitants slowly, and be sure not to overstock.
 

Maintainence for this tank will be surprisingly simple. Top off evaporation with fresh water. Clean and empty the skimmers collection cup on a regular basis. Most importantly, do a one gallon water change once per week or so. The frequent water changes eliminate the need for trace element additions, kalkwasser additions and heavy skimming.
 

That's it. For around $200 or so you can set up a nano reef that will thrive with only 10 minutes of maintenance a week. The main hurdle to overcome will be the temptation to overstock it; otherwise, it should be a dream to maintain.