Google has published an article on the Google Webmaster Central Blog explaining the relationship between the Googlebots and crawled websites.
I have to say that it's somewhat cheesy the way it has been addressed by emulating a conversion in a hot date between the website and the Googlebot. However, it's worth reading as it explains how Googlebot interacts with websites and how it navigates through them.
For example, if Googlebot is crawling for web search it ignores .JPG or .MP3 files, or if it's crawling for Google Scholar it prioritises .DOC or .PDF files.
The article also addresses other subjects which are continuously discussed in the search engine optimisation world such as file extensions, gzip compression and the robots.txt file.