This is the list of Star Citizen Alpha 2.0 emotes as of December 2015:
/agree
/angry1
/angry2
/angry3
/attention
/blah1
/blah2
/bored1
/bored2
/bow1
/bow2
/bow3
/bow4
/bow5
/bow6
/burp
/cheer1
/cheer2
/cheer3
/cheer4
/cheer5
/cheer6
/cheer7
/cheer8
/chicken
/clap1
/clap2
/clap3
/clap4
/come1
/come2
/come3
/come4
/cry
/dance1
/dance2
/dance3
/dance4
/dance5
/dance6
/failure
/flex1
/flex2
/flex3
/flirt
/gasp1
/gasp2
/gasp3
/gasp4
/gasp5
/gloat1
/gloat2
/gloat3
/gloat4
/greet
/laugh1
/laugh2
/laugh3
/point1
/point2
/point3
/point4
/rude1
/rude2
/rude3
/salute1
/salute2
/sit
/sleep
/smell1
/smell2
/stand
/threaten1
/threaten2
/wait1
/wait2
/wave1
/wave2
/whistle1
/whistle2