Pothos (Epipremnum aureum). There's a reason people have grown this plant for so many years (some plants have survived for decades): You can forget you even have it, and somehow it still keeps right on growing.
This leafy vine can grow up to 40 feet long out in the wild, but in your living room, you can expect it to grow several feet. Keep it full and bushy by periodically trimming the longer leggy vines, providing bright but indirect light and deeply watering it twice a month.
Tip: If you forget to water enough, this plant will simply wilt. If that happens, thoroughly soak it and remove any dry or dead leaves, and it should perk up fairly quickly.