Pickled Onions Spices

[pickleandpreserve]

I've git a big sack of pickling onions to get through and am looking for inspiration..
Which spices are people using to flavour their pickling vinegar?
I've just made a batch of onions using fresh ginger, mustard seeds, peppercorns, cinnamon and some garam marsala mix (not ground), and wondered if anyone's got any other favourites which might be worth trying out?

[PottyPot]

I like to pop a few split chilli peppers into the vinegar. Certainly warms you up