tedster - 8:56 pm on Sep 1, 2010 (gmt 0) [edited by: tedster at 8:59 pm (utc) on Sep 1, 2010]
I see lots more to SEO, like fixing server issues, modifying the CMS, knowing when the stats are inaccurate and discovering how to correct that, consulting for corporate change so that all areas of an enterprise that touch the website can collaborate effectively... I could go on and on.
All that improves SEO and definitely offers ROI. But I wouldn't make any kind of revenue share proposal for those services.
[edited by: tedster at 8:59 pm (utc) on Sep 1, 2010]