I bought a fantastic script today, one that does just about everything an online marketer could want with links -- it tracks, redirects, cloaks, embeds cookies, split tests, and some other stuff that I haven't figured out yet...I'll post tips here as I learn more about the power of this tool.  Go take a look at this, but ignore everything on the second page except videos #1 and #3 at first (video #2 just talks about graphs and statistics).  The text is a little unclear, but the videos give you a glimpse of the true nature of this script -- you can go back through the text later.