I don't know about cache but the strange thing is I can not see the impressions in Google website for couple of days back and people do come from google which I have seen in Google Analytics, so something is going on with Google.
Link Building is the process of creating inbound links to ones own website. This can be done by reciprocal links, being listed in e-zines, newsletters, directories, search engines, etc. Link building is one of the best ways to make your site popular. There are few types of linking one of which is reciprocal links. Reciprocal links or link exchanges is the process where two webmasters agree to show the other's link on their website. After link building when the number of sites which link to a particular site is known as link popularity which helps in the search engine ranking of a website. There are many advantages of link building. 1. Link building helps in getting quality traffic from relevant sites which increases sales. 2. Also when there will be high quality incoming links the site will also be seen as a valuable resource. 3. Link building helps in creating awarness, visibility and credibility of your site. 4. The site also obtains wider search engine exposure. 5. It also helps the website get indexed by search engines.