Mine's not as fancy as those above, but depending on your filter, you may be able to aim to outflow over your plants, which is what's working for me.
This is just a bit of wood hooked over the open output at the back of a fluval flex. Left to right is Anubias Coffeefolia, Java moss (?), Buce sp., Java Fern, Mondo Grass, and a torn up moss ball at the back. All are growing well under the lid - I think the humidity really helps.