And if you think this method is going to get saturated - think again.
When you search google groups with a query "1 of 1", you're only going to get forum pages that so far only have 1 page. As soon as it's filled up, it gets filtered out of future search results for that query and it gets replaced by fresh results.
And there are new forum pages being created all the time.
These links are really great - you get the high PR, you get the relevance and you get the anchor text.