This is another of those areas in the hobby over which aquarists have differing opinions. I fully concur with 1077's general statement that the less stuff added to an aquarium, the better. However, there have been some scientific strides made in the last decade, and there is no reason why aquarists should not benefit. One does still have to be careful, because some products that claim this or that may be more harm than good. I won't get into that, but will make some observations on what Gouramikeeper83 has specifically asked about, namely biological supplements to cycle a new tank.
Several years ago, Dr. Timothy Hovanek developed a process for bottling live bacteria, including nitrosomonas and nitrospira, the two bacteria responsible for the nitrification cycle. Here's a link to his organization: http://www.drtimsaquatics.com/One_Only/OneOnly.html
Dr. Hovanec received his PhD in the field of phylogenetics and detection of nitrifying bacteria. He led the team of scientists that discovered that the second phase of the nitrification cycle, converting nitrite to nitrate in the aquarium, occurs through nitrospira, not nitrobacter, bacteria. I only toss this in to illustrate that Dr. Hovanec is a scientist with considerable knowledge in this area. If you're particularly scientifically-minded, here is a link to the abstracts of his work: Scientific Papers
The shelf lfe of Dr. Hovanec's product is six months, or 1 year at 50F, longer if refrigerated; it contains live nitrifying bacteria.
Seachem have developed what appears to be a very similar product, also containing live bacteria, and called "Stability." Here is a lnk to their scientific information: Seachem. Stability
I recall a thread containing an email from someone at Seachem clearly stating the bacteria properties of Stability; I can't find it now, I think it was another forum. But no matter.
I'm not saying Stress Zyme is or isn't similar, but I would point out that it is a water conditioner (according to the API site) and this puts me on my guard. It also claims to "break down organic compounds" and some products that do this raise ammonia levels. Just a caution, I offer no opinions.
Tetra's "Safe Start" is said to be the same as Marineland's Freshwater Bio-Spira, based on Dr. Hovanec's formula as I understand it. I've not used it.
Whichever product, introduce only a few fish into the tank. The bacteria, however they are introduced, must be sufficient to handle the ammonia and nitrite resulting from the fish. Of course, plants do all this naturally and that is still the best and safest route. Nothing "foreign" need be added.