Lonely Planet (www.lonelyplanet.com/iran) Destination information, hotel bookings, traveller forum and more.
Iran Tourism & Touring Online (www.itto.org) As close as Iran comes to a tourism website with some informative links.
Easypersian (www.easypersian.com) Learn some Farsi.
Iran Chamber Society (www.iranchamber.com) Good for high-level coverage of the arts.
Tehran Times (www.tehrantimes.com) Iran's English-language news site and newspaper.
See You In Iran (www.facebook.com/SeeYouinIran/) Worth signing up to this FB group posting all kinds of useful stuff for Iran travellers.