It is my understanding that Google gives full benefit of the first link from any domain to my domain. Second and third, etc., links have little value in Google. With that in mind, what linking benefit is derived from a blogroll link that links from many (all) pages in a blog? It appears to me that if I gain many blogroll links back to my domain, in a short period of time, I will develope a strong spam signature at Google. I will appreciate the benefit of anything that you have learned about this issue.
sitewide link would have somewhat greater value then those from a single page. remember relevancy is always key for link value.