Airports
Strasbourg international airport, Entzheim (15km away from the city centre)
Baden airpark, Baden-Baden, Germany (60km away from the city centre)
EuroAirport Basel-Mulhouse-Freiburg, Mulhouse (130km away from the city centre)
Frankfurt airport, Franfurt, Germany
Charles de Gaulle, Paris, France
Orly, Paris, France
You can also search for flights to XWG (IATA code for Strasbourg train station), you can get some combined flight+train tickets through Paris Charles de Gaulle this way.
XER (bus station next to the Strasbourg train station) can also bring in some interesting offers, e.g. plane to a nearby airport and then bus shuttle to Strasbourg.
Train
SNCF: http://www.voyages-sncf.com/ (French train company)
Deutsche Bahn: http://www.bahn.de (German trains)
Bus & Tram
Web site: http://www.cts-strasbourg.fr/
Going back to GUADEC/2014