There is a negative side to having your PageRank restored, or maybe depending on your niche it can be turned into a positive.
Many of the blog comment tools are based not just on the highest ranking pages for a search term, but resorting pages based on PageRank.
Whilst my content ranks well, when such lists were sorted by PageRank of the pages, or of the domain, having a -2 or -3 penalty was greatly reducing the amount of manual comment spam I was receiving compared to how much it could have been.
For the last few months I have had between 1000 and 2000 visitors per month who I am fairly sure were here primarily to link drop.
How do you monetize comment spammers?
Well possibly sell them some tools to do it more efficiently, if you can identify them by referrer ID.
Hey Comment Spammer, You Need Better Spam Tools
Then you provide them with a bunch of free and paid alternatives that all have some kind of revenue attached.
Shephan listed a few comment tools recently and many of them have an affiliate program.