Lord of the Ring Online is the only decent commercial game based on LoTR. It offers a pretty much huge world, lots of things to do, and is pretty much casual-friendly.

Battle for Middle-Earth (1&2) were huge failures, the hack n' slash games based on the movies are somewhat entertaining, but they're quite short and offer no replayability.

If you're not looking for commercial games, then the mod the Third Age for M2TW is pretty good, though the quality varies. It also lacks flavor: a LotR TW would have deserved much more traits, ancillaries, and other stuffs. Then again, it has been released quite recently and will probably improve with time.

The LotR maps for HoMM3, HoMM5 and Warcraft 3 (yes) were also quite good and entertaining.