Here are some links to some sites I enjoy.
If you'd like to exchange links, please contact me.

The Bowser Shrine
This is an amazing site for all things King of the Koopas. It is definitely a website worth checking out. I especially appreciate the History of Bowser page.

Toad's Castle
I've been going here for years. A very solid Mario Fan site.
When I think Mario Fan Site, I think Toad's Castle.

NES Times
I think this was the first NES Fan Site I ever visited. (Or at least one of the earliest I remember).
It hasn't been updated in awhile, but still worth a look.

SM64.com
A site dedicated to Super Mario 64. Tons and tons of contents.
Sort of a role model for me and this site.

The Video Game Atlas
Love this site, tons of maps of NES and SNES games, as well as for abunch of other systems.
I used some maps there by Zeric to design SMB3.com, so a thanks to Zeric.