http://www.maxcape.com/nr - A website where you can see how far you are to max/comp cape, also can design your own cape here if you want.
http://www.runeclan.com/ - You can track the clan or your individual progress here, this is my personal favorite tracking site.
http://runetrack.com/ - I think everyone knows about this but its personal tracking that the clan use for tracking everyone.
http://www.indecentcode.com/ - I love this site, a bit confusing at first but when its set up you can see what levers are nearest to 99 or a target along with a load of other features.
http://runetracker.org/ - Similar to runetrack but needs manually updated
http://skillershub.com/hiscore - A tracking site for skillers with a highscores for level 4's

http://www.runescape.com/community - The rs homepage, for news and the official rs forums.
http://runescape.wikia.com/wiki/RuneScape_Wiki - A full wiki for Runescape, need to know something about the game? This is where I look first.
http://www.tip.it/runescape/pages/view/skill_calculators.htm - Some great calculators for skills, the site also has features covering the entire game.
http://rsplayers.wikia.com/wiki/RuneScape_Players_Wiki - Create a personal profile here, show everyone about your RS career and keep them updated.
http://runeapps.org/home - some useful apps to help with RS gameplay, the celtic knott solver and the drop logger are my favorites.
https://sites.google.com/site/proulxssolver/ - When doing clues, I am usless at the puzzle boxes. Let this help you out if you are the same
http://runezone.com/radio/ - Good to listen to time to time, The site also has loads of useful features and forums.

https://itunes.apple.com/gb/app/swiftkit-for-runescape/id440476684?mt=8 - Swiftkit for iphone, keeps you updated through the day along with other features. I use this constantly.
http://www.runescape.com/companion_app - The official RS app, good for talking to clannies when on the move