http://i858.photobucket.com/albums/ab148/VanitusSpriter/Deathclaw_Breeding_Grounds.png?t=1297459221
Location highlighted in *Red*.
Notable Loot: Remnant's Power Armor, T-51b Power Armor, T-51b Power Helmet, Multiplas Rifle
The Deathclaw Breeding Grounds is a small area on the coast of the Legion island to the South East. It is surrounded by large mountains and is filled with Xander Root and Broc Flowers. It is recommended that you reach Level 20 or higher before taking on this area, and that you have an Anti-Material Rifle, a lot of .50MG ammo, a few Stealth Boys (Not Needed if you wish to fight head to head.), and several Stimpaks, Super Stimpaks, Doctor Bags, etc.
When first entering the Breeding grounds, you will be walking up a small hill, so you will be blind to the first 3 Deathclaws that will attempt to attack you. The easiest way to kill them is to use your Anti-Material Rifle and take out their head or legs, and the easiest strategy for handling these first few Deathclaws is to get their attention, then run to the water below. They will turn back to their spawn point. That will be your chance to shoot them from behind with your Anti-Material Rifle. Repeat this process until both Deathclaws and the Young Deathclaw are dead. As you enter the Grounds, you will see a few more Deathclaws in front of you. It is suggested that you use a Stealth Boy to get onto the large rock beside you to scout the area and to snipe the visible Deathclaws. There will be 1 to the far East of the area and 3 to the South from there. Take out the ones you encounter, then head to the one to the East. After killing that one, I recommend that you move to the higher rocks or cliffs to the West, and snipe the other 3 from there. Now, get to the cliffs beside the water and head South, following the cliffs, and getting as high as possible on them. Very soon, you should be able to look to the East from there and see 10+ Deathclaws grouped together. There will be 1 Alphamale, 1 Mother, and several Young and Normal Deathclaws. I recommend staying high on the cliffs, ducked down, and snipe the Deathclaws from there with your Anti-Material Rifle or a Silenced Sniper Rifle. Once all of those Deathclaw are dead, there might be a few more scattered around the area, so be careful, and crouch around the area until you are sure that there are no more Deathclaw. Once all of the Deathclaw are dead, go back to the place where you killed the 10+ Deathclaw and have a look around. You should see 2 dead Wastelanders laying on the ground beside the rock. (They may be under the dead bodies of the Dearhyclaw.) One will be wearing T-51b Power Armor and the other will be wearing the Remnant's Power Armor. Beside them, you will find the Multiplas Rifle. Loot the bodies as you like, and finally, you will find several Deathclaw Eggs to the South East wall of the Breeding Grounds. Those can be sold for 400 Caps each but weigh 7.00 Pounds each.
Let me know if this helped you and if I should post any more.
Screenshots
http://i858.photobucket.com/albums/ab148/VanitusSpriter/DeathclawArmy.png?t=1297486050
http://i858.photobucket.com/albums/ab148/VanitusSpriter/DeathclawsUnderCliff.png?t=1297486113
http://i858.photobucket.com/albums/ab148/VanitusSpriter/EnclaveplusMultiplas.png?t=1297486186
http://i858.photobucket.com/albums/ab148/VanitusSpriter/DeadBrotherhood.png?t=1297486215
http://i858.photobucket.com/albums/ab148/VanitusSpriter/DeathclawFlames.png?t=1297486242