I've just searched the word 'Chess' on Google and I'm going to sort through some of it to see whether or not it is useful.
I really recommend using Chess.com as your primary website for chess and all things regarding chess, everything and I mean everything to do with Chess can be found on this site.
Alternatives include ChessCube, ChessKids and ICC(Internet Chess Club) All of which are very useful.
If you think you need to improve your tactical play, learn new motifs and practise endgames I highly recommend ChessTempo - packed to the brim with all the latter.
Reading online PDFS and eBooks also aid improvement so I would recommend sites such as The Amazon Kindle library and such like.
But, nothing beats practise and you will find no better place than right here at Chess.com
Stay classy San Diego.