Allies
You may have Ork allies, or if your opponent agrees, you may have allies from Chaos Cult and/or Imperial Guard. If you choose the Imperial Guard, you may ignore the command structure, as most officers will have been purged from the army long ago, but you are not allowed to use reserves or pre-battle barrages.
Chaos Space Marine Dreadnought
Chaos Space Marine Dreadnought must be used with care due to the special rules of insanity affecting them. My favorite is to equip them with either of two combinations: One is Power Scourge and twin autocannon, the other is Thunder Hammer and twin autocannon. I often add a Havoc Missile Launcher.
Land Raider
Big, carries troops, four lascannons and two heavy bolters.
Rhino
I consider the Rhino one of the most flexible vehicles available to Chaos. One of my favorite vehicles is a Rhino possessed by a Daemon of Khorne with Ablative Armour, Reinforced Armour, Supercharged Engines, and Destroyer, a Troop Mower, and it's cheap. Another Daemonic Possession for this vehicle would be a Daemon of Slaanesh, a Warp Amp, Ablative Armour, Reinforced Armour, and Supercharged Engines, or if you're low in points, just the Daemonic Possession and the Warp Amp..
Predator
The different varieties that this tank can be used in make it the most versatile and the most useful vehicle available to any Marine army. You can go with only a single autocannon, and have a tank that costs less than 100 points. Or you can have a tank sprouting four lascannons at 210 points. Or several combinations in between. My favorite is twin-linked lascannons in the turret and heavy bolters in the sponsons, 150 points. The Predator can be used several different ways as a Daemon possessed vehicle. I like to arm it autocannon, two heavy flamers in the sponsons, Destroyer, Ablative Armour, Reinforced Armour, and Supercharged Engine. Another good Daemonic Possession is Nurgle, with Nurgle Infestation, autocannon with heavy bolters or heavy flamers in the sponsons.
There are several other combinations that you can use with Daemonic Possession of Chaos vehicles.