There are a couple of ways to "jump start" the nitrogen cycle in your new aquarium. If you decide to follow one of these methods, you will still need to wait for the tank to finish cycling, but you won't have to wait as long. The limiting factor in cycling a new tank is the time it takes for nitrifying and denitrifying bacteria to mature and become established. So, if you can introduce some of these bacteria into your new tank, you can get a head start.
The first method involves taking some of the gravel from an already established tank and putting it in your new tank. In an established tank, nitrifying and denitrifying bacteria will adhere to the gravel. So if you can borrow some of that tank's gravel, you can "jump start" your own. Remove about a cup or two and place them in mesh bags. I have used mosquito netting and panty hoses with knots tied at the ends. Place a couple on the gravel in your new tank, and then, if you are able, dangle one in your filter. Leave them there for the duration of the cycling period.
If you acquire your gravel from a local fish shop (LFS), be cautioned that their tanks are usually very unstable because of the large volume of turnover.
Another alternative is to borrow a filtering pad from another already established tank and to use it for your new tank's filter. In my opinion, this is perhaps the best method. Or, you can simply remove a filter from an already established tank and set it up on the new tank. Just be sure to provide an ammonia source or the bacteria will shortly die off from starvation. "Seeding" an new filter with an old or established filter pad/sponge has reduced the cycling period from 4 to 2 weeks for me.
If you don't have access to an already established aquarium, there are commercial alternatives. Within the last several years, several products have become available that contain colonies of denitrifying bacteria. Some of these include "Stress-Zyme," "Fritz," and "Cycle." In theory, these products should give your tank a "jump start" on the colonization of your tank. Personally, I don't know how effective these products are. I've heard mixed reports; some report success and other say they didn't work at all. In principle, however, such products should work well. I can see how they might not work though, because denitrifying bacteria cannot live indefinitely without oxygen and food. So, if the product is very old or has been exposed to high or low temperatures, I'd imagine that the products could be rendered ineffective. Unfortunately, these products don't come with a freshness date, so there is no way to know how old they are. Marineland recently developed a product that will cycle your tank in less than 24 hours. Bio-Spira is kept refrigerated and can only be purchased by stores who buy a special refrigerator from Marineland.
Whatever way you decide to cycle or jump start your tank, be conservative. Feed your fish sparingly for the first few weeks, and keep an eye on the ammonia and nitrite levels, performing 25% weekly water changes. Respect the nitrogen cycle and you'll be happy you did. □