MeCCG.net: This is probably the most useful website about Middle-Earth.It contains a lot of information about the game, and has a large forum (which is no longer very active, but still contains a lot of tremendously useful information). More importantly, it also contains the old site of the Dutch Council, which contains the official rules (including errata and clarifications), complete card descriptions, details about winning tournament decks, and a whole lot more.
Council of Elrond is the official Middle-Earth website. The Council of Elrond is “the world-coordinating body for the Middle-earth Collectible Card Game”, and an organisation run by players. Apart from information about the Council, the site also contains the official rules, and a large and more active forum.
The Guild Companion lists various variants for Middle-Earth, including some variant solo rules.