Results generated from "viral marketing" are not going to stay for a time long. I think patience and hard work will do a good job in promoting your site. However, there are some tools and softwares but you must read their reviews before using them. I haven't tried them yet :P
You don't "do" viral marketing. You can improve your chances of a clip or blog going viral by using popular and/or "hot" items and launching supporting comments/posts on as many relevant sites as fast as you can, but that is about it. If a subject is doesn't lend itself, it won't go viral no matter what you do.
Viral marketing needs not just a lot of effort but a number of people to be effective. The question now is how to attract a lot of people to make your marketing go viral. One way is to promote free promotional products or render free services.