VLAN and MPLS are common, as well as .1P/.1Q and DSCP. Then you can find hybrids like MPLS-VPN and S-VLAN, and then the tunneling protocols like GRE, L2TP, VXLAN, DOVE, QinQ, OTV, NVGRE, PBB-TE, SPB, VLL, etc. And most of this is just Ethernet, there are often similar standards for different L2s like wireless networks.
