The serpent spam thing is a joke really. Its tough to play against but the ones who usually are so unimaginative that they go on the internet to make their lists don't have the higher-thought capacity to actually put that kind of list to good use. Getting up close and tapping the back of the WS with a krak grenade or two always works best - something that is really easy to do when your dumb opponent just parks them on the back edge and thinks he's going to shoot down anything that comes hunting it.
My favorite Eldar lists right now are ghostlists with wraithguard and wraithblades.
It goes kinda like this.
(Not using Iyanden sup either)
Spiritseer
Farseer on foot
10x WG with cannons
10x WB's with axes and shields
5x WG with scythes in a Serpent w/HFs and Ghostwalk.
1 Hemlock (Because I love how everyone basically ignores it because the internet says its bad)
1 WK stock
2 WL's with swords and BL's.
Now the internet will tell you that this list is terribad. The internet is full of sh!t. This list is incredibly tough (with only two models with a toughness less than 6) and hits very very hard. Even bullet shot out of this army is AP2. Don't forget to spirit mark stuff. It really makes a difference.
This army's crowning glory was obliterating a 3 knight list. Oh how glorious that was.