Lotus Vale (Mirage Block), a land that requires you to sac two untapped lands to play it. Basically, the major use for the blue spell Stifle; that gives you four mana at turn two. If you're somehow lucky enough to draw four of these, an Island, and four Stifles as your first nine cards of the game, at turn five you'd have thirteen mana, which is more than enough for... well, anything.
Lotus Petal (Tempest Block), a
common, which lets you sac it for one mana of any color... and you play it
free. A massive anomaly: it's restricted (to one per deck) in Vintage, but perfectly legal in Legacy and Block! Bollocks.
Lotus Blossom, a potentially massive mana generator for two mana. However, remember that it must stay in play, and is a one shot use, and requires you wait around for it to gain much use. Even by the time the first turn after rolls around, you gain something out of it, but by then, what's to stop an opponent playing Shatter?
Gilded Lotus (Mirrodin Block), a five-mana clone that you don't have to sac. Can you say 'crazy powerful'? Made more ludicrous by the lack of restriction to it. Great in block play, if only cause it lets you speed up the process of generating Darksteel Colossus, etc. by
three freakin' turns.
Lotus Bloom, which is essentially an exact clone of Black Lotus, minus the fact that you must play it by Suspend (so it sits out of play for three turns before it comes in) -- but it's still three mana for free, making it incredibly versatile. If you're still alive by turn three, three mana lets you pull a six-mana spell, and do you know how many spells there are for six mana or less that are awesome? A lot. Planar Cleansing, Jokulhaups, and Wrath of God for mass destruction, or there are tons of six-mana creatures that I know could benefit from coming out faster.
But I never lost a game with that deck even against the "professionals" of the school