I recently happened across a spam goldmine. My eyes widened with anticipation as I watched SEOquake report no less than 21 PR7 pages, 30 PR6, god knows how many PR5 etc. Pages are auto-approve. The topic is coding and development. All pages are 100% clean - later, though, I found the reason for this. Every time one of the pages is modified, an email goes out to everyone who is subscribed to the page, which is always at least the webmaster. So I am in a situation where I can get any number of massive PR links, but for a period of only 24 hours each (that's how long the last one survived anyway). So my issue is this: Is it worth leaving links, knowing they'll be gone in 24 hours? The link I left the first time got indexed very fast (3 or 4 hours) - as you would expect for PR7!