This is less common with the free sac outlets for obvious balance reasons
There are cards that trigger other special abilities whenever you sacrifice a land (like making extra creatures to fill up your board) and cards with various Landfall abilities that do cool things whenever you play a land (like getting an extra combat step)
Because time and space are funny things and so are dinosaurs
This Phyrexian monstrosity grants its equipper a buffet of buffs: 5/5 , first strike, trample, haste, indestructible, and exiles creatures it deals damage to
The Bayou Mysterious Swamp | Location The Bayou has a cool ability for a simple one-cost location
Fortunate Few [Dragon deck]: That's a pretty sweet board wipe, and if all you have is one gigantic dragon and lands, you lose nothing