I have one suggestion (mostly for exchangers). It's about creating a break on the supply's increase, just not a purely artificial one.
I wonder whether the exchange of coins (for physical stuff) could be done at a rate dependent on the number of spends?!
For example, exchange 1 freshly minted (this is seen in the coin's history) coin for $0.001, exchange 1 coin which was spent 1 time for $0.002, exchange 1 coin which was spent 2 times for $0.004. And so on...
Why? Because I wonder whether this kind of natural cost (= the number of spends / the circulation of coins, rather the their minting) would create a break on the supply. Of course, those who create coins could also artificially spend them inside their computers.
This means that there would have to be some sort of public markers which are considered valuable by the public. For example, if a coin was spent once to a given list of entities / peers (like exchangers), it gains 1 point of exchange value.
Since exchangers exchange coins for physical stuff, this could create a break.
I also wonder whether the markers could be simple peers whose public value is voted by other peers?!
It's all really fuzzy now and too early into the system.