Thoughts on Allies?

Hey everyone, I am really starting to look into bringing allies into my army. My first thought is bring our only battle brother into the mix Eldar. I have thought also about IG tank heavy to take fire off of our frail vehicles and Wolves to bring in thunderwolf cav, and a drop pod with logan and the melta gang to take fire off of our frail vehicles. Desperate allies of course have the dangerous downsides. Right now I have brought a 5-10 man squad of eldar rangers and a farseer or eldrad to negate any enemy psyker. I was curious what is everyone else bringing and should I stick to my original thought and expand my Eldar side and if so with what?
Thanks in advance
Tater

I have played a couple of games with a mix of Eldar and DE. Loved the combo. A couple of things stood out for me. Love rangers/pathfinders. Great because DE doesn't have any infiltrators and people continue to try and remove them even with their 2 up cover save. They draw alot of fire and can put down characters and small squads. Eldrad is still king! Especially with some guardians behind a defense line with the quad gun. But most of all, War Walkers. These guys are just too good to pass up. keep them near Eldrad and guide. Man guided WWs with scatter lasers puts the hurt on anything. Also really like the Eldar Missile Launcher. People see war walkers and they immediately make them a priority. Might take some heat off of your raiders....