The two with the thin pads look like prickly pear, but i could be wrong. The other may be barbed wire cactus.
Sarah

Thanks Sarah for your help. The one on the right may be a barbed wire cactus as you said.

"Prickly pear" is the common name for all thin paddled opuntia and since there are about 250 species of this genus, that doesn't narrow it down too much :-) Unfortunately, a good many of them produce yellow flowers as well. One possibility is O. robusta, another is O. santa rita (syn. O. violacea). Are these growing outdoors naturally or as houseplants? That could narrow things down a bit......

I think the Euphorbia is Euphorbia Ferox and the other ones are opuntias.

Bottom left is Cow's Tongue?

I forgot about this post.
Gardengal, they are grown outdoors. The top may be O. robusta but I doubt an O. violacae. I will post some of my o. violacae later as I am unsure about them also.
Cactus lord, I have not found a Euphorbia Ferox that looks like mine but I am still looking. It does have little yellow flowers along the spines.
Daffodillady, I do believe the bottom left is some form of cows tongue.
Thanks everyone for your help.