Link building is extremely time consuming, and can at times be quite frustrating. So I've put together a list of some of my favorite articles out there on link building to help others searching for quality information. Feel free to add your own in comments.
Stuntdubl's 12 Different Types of Links and How to Get Them. Todd Malicoat put together a nice list of the various kinds of links that are out there, along with some ways to acquire each. This is important since we want a site's link profile to be varied. If all of your links come from one source (all directories, or all social bookmarks) it can obviously set off a red flag.
How can you determine if a particular site or page is passing link popularity? A Webmaster World thread addresses that. Don't waste time trying to garner a link that the search engines have discounted.
I'll add Vandelay Design's 99 Ways to Promote your Blog for Free even though it's not all link building. But if you're specifically looking to increase links and traffic to your blog it's a good reference. My blog's new, so forgive me for not tackling the 99 ways yet!
SEOmoz has a nice piece on buying links under the radar. This is changing hat colors a bit, but there's benefits to purchasing links beyond "link juice". Even if "nofollowed" you can increase your site's traffic with some decent links. Even if your goal is traffic, you can be penalized for purchasing links if caught, so read Rand's post.
There are a lot of tools out there to help with link building. Instead of rehashing them all, which has been done to death, I'll point you to a Search Engine Land link building tool roundup post.
A great resource is Sugar Rae's interview on link building with 11 experts. I especially like Eric Ward's answer to Question 11.
If you're interested in link baiting, read Andy Hagan's Ultimate Guide to Link Baiting. I just linked, so I guess he knows what he's talking about :)
There's a few. I may go back and add more in the future, so bookmark it.
