• Echar la casa por la ventana: To spare no expense
• Echar el cuento, el caballo, el ruco or los perros: To seduce a woman.
• Echarse un polvo: To have sex
• Echarse a alguien: To murder someone (narco slang)
• Echar a alguien: To fire or through someone out of a place
• Echar al agua: To snitch on someone
• Echar flores: To praise someone
• Echarse para atrás: To back down
• Echarse un samuel: To look furtively at someone’s private parts
• Echarse un pedo: To flatulate
• Echar tierra a algo: To hush or forget
• Echarse la soga al cuello: To get married or tie the knot
• Echar raices: To settle down
• Echar carbón: to incite someone 
• Echar leña al fuego: Similar the last entry
• Echarle el guante a alguien: To arrest someone
• Echar para el saco: To learn a lesson
• Echar una mano: To help or give a hand to someone
• Echar patas: To disappear

These are all I can remember off the top of my head. There are many more expressions using the verb echar.