301 URL Shorteners such as Bit.ly are a great way to boost the rankings of your site if used properly with a program such as GSA.
These 301 shorteners add an extra layer of protection to your site when using them, and are a great way to help rank parasites.
In this service, I will take your URL (one only please) and create a tier of 301s from services such as , Bitly and also Trim. These will then have links built to them as a tiered structure. The benefit of this is that when you point a GSA blast (or similar) to the tier 2 links, it passes the link juice through to tier 1 and since these are so powerful, it'll help your site. Tier 1 will consist of ten short URLs that goes back to your original URL. Tier 2 will consist of 30 URLs to each short URL in tier 1 (300 short URLs in total for tier 2).
If you are using these as a spam technique for your own site, I'd suggest that you point the links to a web 2.0 if your site is fairly new. This is also a cheap and cost effective way to rank YouTube videos, and from a a personal test, my own video jumped from page 6 in the results page to page 1 when I used these 301s with GSA.
Please not however that no ranking guarantees can be given since the difficulty of ranking a keyword isn't taken into account in this. Also, I can't be sure of the quality of the GSA lists you might be using, which can alter the ability of the site to rank.