brief history / a bit of context

electronic musical instrument 1870 - 1990
1870-1915: early experiments / 1915-1960: vacuum tube era / 1960-1980: integrated circuits / 1980-present: digital
russollo and the art of noises (1913)
some historical electronic instruments: telharmonium, theremin, electronic sackbut, moog synthesiser, synclavier, emulator
early electronic music studios: music concrete (late 40's, paris) and electronic music (1950's in germany)
computers get involved - mid 50's - now we have tools like ableton live -- chuck -- PD -- max
a range of options: electronic instruments, tape, portable synthesizers, computers / live processing, extended instruments, hacking / circuit bending
custom performance instruments and interfaces - electronic music instruments

you could read this short article on live electronic music performance
or this longer article on interactivity and live computer music
Interesting timeline of electroacoustic music
for a more detailed look at the history and practice of electronic music, you could read:
Electric Sound, by Joel Chadabe
Electronic and Experimental Music, by Thom Holmes

some different approaches to live performance

instrument and tape:
Davidovsky - Synchronisms #1 (1962) -- Synchronisms #10 (1992)
more info about this series of pieces is here

live processing / extended instruments / experimental approaches:
Jeff Kaiser - composer, performer, improviser, music technologist and media artist
in his duo with David Borgo - KaiBorg: Harvesting Metadata - video here
you can read a paper about how he converted his performance system from hardware to software here
check out laetitia sonami and the lady's glove -- some performance videos are here
also Imogen Heap - talk / performance with musical gloves
mostly robots -- a performance oriented electronic band talk / demo here - performance video here - sponsored buy native instruments
Tim Exile - performance videos here
the always compelling Shawn Greenlee
the princeton laptop orchestra -- also know as PLOrk
or check out some of my live performance work

a few references

Bongers, B. (2000) Physical Interfaces in the Electronic Arts. IRCAM Centre Pompidou.
Chadabe, J. (1997) Electric Sound: The Past and Promise of Electronic Music, Upper Saddle River, Prentice Hall.
Dean, R. T. (2003) Hyperimprovisation: Computer-Interactive Sound Improvisation, Middleton, A-R Editions.
Holmes, T. (2012) Electronic and Experimental Music: Technology, Music, and Culture, Routledge.
Hosken, D. (2010) An Introduction to Music Technology, Routledge.
Manzo, V. J. (2011) Max/Msp/Jitter for Music, Oxford University Press.
Miranda, E. R. & Wanderley, M. M. (2006) New Digital Musical Instruments : Control and Interaction Beyond the Keyboard, Middleton, Wis., A-R Editions.
Rowe, R. (2001) Machine Musicianship, Cambridge, MIT Press.
Schnell, N. & Battier, M. (2002) Introducing Composed Instruments, Technical and Musicological Implications. Dublin.
Wanderley, M., Battier, M., Ircam & Centre Georges Pompidou. (2000) Trends in Gestural Control of Music. Paris, IRCAM Centre Pompidou. CD-Rom.