Though item sockets are quite common in Diablo III, the only thing that can be socketed are the four types of [[gems]], and there are only two three types of socket values with each gem: [[weapons]], [[helms]] , and "other." This seemingly leaves a lot of room for growth, and it's expected that socket bonuses will be more varied, and that more socketable objects (perhaps [[jewels]] or even some new version of [[rune]]s) will be added in the game's expansion(s).