Below are some links that I think are important and useful. If you have more suggestions, please let me know at firstname.lastname@example.org. I can't promise that I'll put all suggestions up but I'm sure there's some I've forgotten.
sweetadeline.net - This site hasn't been updated for quite a few years but is still an enormously great resource, especially all the history of live shows. It's always been an essential and important place for Elliott Smith fans.
alphabet-town.com - An incredible resource that I need to delve into a bit more. Check out the song guide for detailed information on every song that Elliott was ever involved with in any capacity.
Janice Ordal's old Elliott page - Great page with info and fan accounts of some of Elliott's shows.
Elliott Smith Gallery - Facebook page that is a great resource and has awesome photos.
My Favourite Elliott Smith Song podcast - This is such a great podcast. It features well-known people and also people who were close to Elliott talking about their favorite songs of his. Each episode makes me appreciate that particular song a little more than I previously had.
larry-crane.com - Larry founded Tape Op magazine and owns Jackpot! recording studio. He worked with Elliott a lot and is the official archivist of Elliott Smith's estate.
Cavity Search Records - They released early Heatmiser and Elliott Smith records including Roman Candle. Still putting out great music.
Kill Rock Stars Records - They put out so many important records in Elliott's career. One of my all time favorite labels and still going strong today.
Domino Records - They've put out the majority of the UK pressings for Elliott's records.
Suicide Squeeze Records - Great label that put out some important Elliott records.
K Records - I believe they only put out one Elliott recording (co-releasing the Spring Tour '96 cassette with Kill Rock Stars) but they still need to be included because they are K!
Anti- Records - They released From a Basement on the Hill.