Ones I am aware of:
- AirData
http://www.airdata.co.uk/
- Jeppesen (can be internet or 'online' "OpsControl")
- SITA Flight Planning
- LADECO (was this the old Continental system housed at Los Angeles??)
- SWORD (BA in-house - I was told that flight planning was a part of the large SWORD system)
Cheers