Can footer links be used to link out to others sites without any issues? I have heard that a few are ok but I am seeing many sites selling links that have 10-20 of them. Has anyone stepped in hot water with the big "G" this way?
Footer links are a great way to get sitewide sponsorship listings. This is very common place for authority sites to have a section such as friends, partners, or affiliates with an OBL to their site. The anchor text of the hyperlink obviously matters as well.
Footer links are fine in general. The only thing is, you are diluting the PageRank / value by doing so. I would try to keep them under 5 for best results.
Footer link is ok if you link out a few but if it has hundreds of out links, you would meet some penalty in decreasing your PR