The Google API stands for ‘Application Programmable Interface’. As it’s name implies, it is an interface that queries the Google database to help programmers in the development of their applications. The Open Calais API can extract meaning from text for you. You could call it a semantic search engine. It can help you find relevant keywords or tags for your pages. With this you van easily group articles. It can also help you to see if your copy writers articles are actually 'on topic'. If Calais suggest the article is about topic X while you asked your copy writer for an article on topic Y, you know you should be asking for a rewrite. Both relevant tagging and 'on topic' copy can be very useful in your SEO efforts. For WordPress and Drupal there are plugins available that use the Open Calais API to automatically tag every new post or page.
I know Google API used to embed a Google Map into website. Very easy. You can search: "Embedding a map into website". Good luck to you
Nice job cikapero! I didn't realize the number of API's Google had and I've been at this for a while now. Now if I can just find one that will funnel money into my bank account.