Appreciate you are talking about recording percussion instruments rather than sfx, but apart from using a sledge hammer & large wooden mallet I've recently been recording some props using a set of PolyEnd PercPro robot beaters - most recently with an old metal cabinet - who knew playing triplets at 900bpm would sound like a diesel engine!!
Highly reccomend the Sennheiser MKH8020 mics (I'm using a pair inside the cabinet) as they go down to 10Hz and up to 60kHz... sound incredible when captured at high sample rate & pitched down...
Other techniques worth trying: using a high quality contact mic (reccomend Barcus Berry or Trance Audio) but instead of attaching it to the object being played, attach it to other large resonant objects (eg a tamtam or large gong) so that the gong acts as the microphone diaphragm (kudos to Aphex Twin for mentioning this technique) - so you don't touch the gong, it just resonates sympathetically...
Have also heard of an engineer who likes recording drums with a hydrophone in a bucket of water, but not sure about that - could be interesting for an unusual ambience, but I have yet to hear a hydrophone capable of capturing much bottom end....
cool!
do you get a lot ambient noise when recording like that?