It looks like you may have burned your first plant by moving it outdoors to full sunlight too quickly. I've learned this the hard way many times.
Check out Uebelmannia pectinifera for a very nice looking cacti. http://www.cactus-art.biz/schede/UEB...ectinifera.htm
This is one cactus that grows in the light shade of grasses in Minas Gerais state in Brazil and really does not do well in full unfiltered sunlight here in NJ.
Fresh.Salty's second plant is a Euphorbia. http://en.wikipedia.org/wiki/Euphorbia
I didn't look up the species as there are so many. They grow in southern Africa and Madagascar. Many of them are very poisonous if you get the sap on your skin. Many are really interesting looking. Many different growth forms in this genus. Crown of Thorns and Poinsettia are both Euphorbias.