There's not much.
There used to be once a week service to Saba on Winair, but I can't find it now.
There used to be Wednesday service to Nevis on Tradewind, but I can't find it now.
There used to be occasional service to St Thomas on Tradewind, but I can't find it now.
There are flights on Tradewind to Antigua, but they require either an immediate turnaround or an overnight.
There may be flights on Anguilla Air Service to Anguilla, but they may require an overnight on Anguilla.
There are flights to Guadeloupe on Air Antilles Express, but they will require either a quick turnaround or an overnight.
Everything else is either a connection in SXM or SFG, the St Martin French-side airport.