I'd personally say jam is too sweet for me, but a number of 'barbecue' type sauces and chutneys, honey, quince and monkey gland are all very good with cheese. Many of the finest restaurants serve such things with their swanky cheeses, so putting them on toast instead of crackers and biscuits would make perfect sense from a culinary, gastronomical perspective, at least.
If anything, it ALL depends on your choice of cheese, I reckon!