I’ve seen various questions about tracking PPC. You can do alot with Google Analytics (see goal tracking) but it’s hard to put all the pieces together to see a clear picture. I personally want to know what PPC network (YSM, MSN or AdWords) is coming to the site, but more importantly what keywords are used, and what keywords convert to sales.
I’ve been rolling out various eBay storefronts and trying new things to separate from the pack, and one of my goals was to get a keyword tracker to feed my SID value in my rover code. This could be adjusted and altered to fit your needs, and is basically just shown how to pass the keyword around in your site, and drop that value in the SID.