You need to do a lot more than the “easy stuff” to see results from your link building efforts.  Search engine results take a LONG LONG time to see good results.  You need to get links from many different sources around the ‘net.  Social bookmarking sites like Digg, StumbleUpon, etc. will send you some good, quick traffic but for the most part, it will only be temporary.  You will need to search around and get links from other sources as well. Think of it like the difference between food you consume.

Blog pings and social posts are like energy drinks with lots of caffeine. Targetted links on high PR sites are more like a balanced diet.

One is fast and the other is slow.

If I want a quick traffic push, I go for pings and bookmarks. But permanent high quality links make much more of an impact, last longer, and also send traffic. The only thing about those is they take a bit longer to see results (and are harder to get).

Think of it like a food pyramid: Sure, I consume caffeine sometimes to give be a boost, but I eat healthy things as my biggest part of my diet because its better fuel.