Pad File Links (Portable Application Description) ~ This is a downloadable (shareware) software that is built for automating things in the business world. These subsets of XML’s can be submitted into the PAD extension directories. So in a sense, this is a directory submission but with a twist and can be powerful for indexing and other linking strategies if used correctly. 

Article Directory Links ~ These types of links are good for linking in a sense that it can give you a great deal of IP diversity which is very important. Article do not hold near the value as they did in 2010, however, they should still be implemented into your strategy. 

Blog Roll (site wide) Links ~ These links use to be a very good tactic in link strategy. Although they don’t hold nearly as much weight anymore, they still hold a great deal of juice when competing for tougher terms and you are having to add to your overall arsenal of diversity. 

Forum Signature Links ~ a good little link building secret used for giving your keywords a bit of a surge in the SERPS. We don’t suggest this as a sole strategy but it is good for certain instances. Using these links are useful for indexing purposes (using them as 2nd and 3rd tier links).

Ad Links & Classified Links  ~ These are great to use on heavily trafficked websites that are relevant to your keywords. Just make sure that you know what you are paying for and that your link is anchored as a “do-follow” inside of your image ad. This method can work for traffic but it can be de-valued by the search engines if you are using this type of strategy too much. Also, these links are often no-follow links. 

Social Links _ The search engines are heightening their focus and weight towards the Social part of the web. So yes, these links are important to have in link building. With the new Google +1 releasing, it’s obvious that this will continue to be an important element of your link building portfolio.

Video Links ~ Youtube, Viddler, and other Video distribution sites that sometimes offer url (addresses) as references. These types of backlinks “can” be effective if not overused for the sole purpose of backlinks. 
Authority Links ~ links coming from websites that hold a great amount of expertise on the worldwide web. The thing to strongly consider here is to make sure that you are getting links from PR4 and above expert sites. Having a high PR in the root domain carry greater weight. 

Web2.0 Links ~ These are great site like Squidoo, and Blogger.com. They are exceptional for posting unique content and receiving a backlink (editorial vote) from. This is because these sites often hold a high pr in their root domain which passes good link juice to your site. 

Classified - Ad Links
http://www.webmasterworld.com/search_engine_promotion/3735151.htm