GoBase
GoBase is a website by Jan van der Steen that contains a large collection of professional games, as well as a number of articles, including study material.
It has a database search engine for searching through the collection and includes an online replayer that can display the games found in the database.
A large part of GoBase, including the replayer, requires an username and password to access. Registration for the username and password is free, however registration must be done from a non-anonymous and non-free email account, failing which extra credentials must be supplied.
Gobase has an RSS feed available. If you use LiveJournal, you can add
the gobase feed to your friends list.