From MonkeyKingRC is this extremely handy Balance Charge Adapter Board.
Plug into the output of your charger using either the XT60 or 4mm bullet connectors and charge a wide variety of batteries with different connector types.
It has the ability to charge XT90, XT60, XT30, T plug and JST in 2S, 3S, 4S, 5S and 6S.
Extremely simple, but great to have at hand in any workshop or pit box.