7. I had forgotten about this site:
Chessdb.com


According to the blurb that made its way into my mailbox
Just to be sure, go through the following list of features of the website:

- over 100 000 chess games in PGN format ready for view in your browser
- over 3 500 chess puzzles which can be watched interactively on your screen
- over 600 hyperlinks to other chess websites
- over 1 200 PGN file downloads sorted by year and event
- over 2 000 opening variants, that can be viewed