The following airline's have based the following for the summer :
Aer Lingus - 3x A320-200
Easyjet - 6x B737-700
Jet 2 - 2x B737-300 [no B757 this summer
, hopefully back in winter for TFS]
Thomson Airways - A320-200
Thomas Cook - 1x - A320-200
And of course aircraft that isn't based but makes an appearance every day :
Bmi Baby - B737-300 / 500
Manx 2 - LET-410
Continental - B757-200
And not lets forget about the big ones ,
Thomas cook - A330 on a Friday to Sanford as TCX12K/L
Fly Globespan - B763 on a Friday to Sanford
Fly Globespan - B763 on a Sunday to Toronto Hamilton
RUMOR'S :
EASY JET - Will be operating A320-200's out of Belfast by X-MAS ??
JET2 - Will be transferring all operations to Belfast City Airport and keeping the cargo flights at Belfast Intl ?? [perhaps to get competition from Flybe , Ryanair]
Many thanks
keep posting you questions and ill try my best to answer
David