A couple of other commonly-used HTTP requests are:
HEAD object protocol
A HEAD request returns the response headers. This is often used to obtain time-stamp data in response headers that can be used by a client to determine whether it needs to fetch an updated object from the server.
POST object protocol
POST is used to upload data to a server, usually to an object like a CGI program that can process it. POST can accept arbitrary-sized data, whereas using arguments to GET are limited to the maximum size of an HTTP request.
HTTP/1.0 was somewhat inefficient, in that it required a separate TCP connection (and hence three-way opening and closing handshakes) for each new request. HTTP/1.1 allows persistent connections where multiple requests can be made serially on the same connection, which improves performance significantly.
The HTTP/1.1 protocol is defined in detail in RFC 2616. MIME, which was originally intended as a standard for encoding binary attachments in email but components of which are also used in HTTP and other protocols, is defined in RFC 2045 and RFC 2046.