@Bobby - its not that simple, but the rough measure most SEOs use is .85 pagerank / number of links on a page - amount of pagerank passed on to linked pages.
http://www.seomoz.org/blog/how-many-links-is-too-many - has a great write up explaining the basic concept.
@Patrick is also right that its complicated. Other factors also affect the relative value of a link such as shown here - http://www.seomoz.org/blog/10-illustrations-on-search-engines-valuation-of-links
Here's a sample to understand how menus/footers can be great or suck for SEO.
pagerank 4 homepage
10 pages in footer that are linked to (assume no other links) - each page gets .85x4/10 or .34 pagerank from the home page
However, the footer is on every page so if the top level children have a pagerank of 2 you get .85x2x9(9 other pages linking to one of the primary children)/10 or 1.53 pagerank passed from the other links in the footer.
At the end of the day - its complicated, but the general rule of thumb is unless you need 1000 links - don't provide that many or segment them a little more effectively. Most SEOs try and stick to less than 100 links on a page.
This where the conversation usually breaks down in to white, grey, and black hat techniques for link sculpting, but I'm not going to go there.