Have you seen CLAM? The distribution was based on funded Bitcoin addresses, rather than their absolute balances. Each address which had a balance (and was not dust) on the snapshot date was granted around 4.6 CLAM... doesn't matter whether the address had 0.001 BTC, or 1000 BTC, they all received 4.6 CLAM.
This method does bias the distribution towards wallets which have a lot of funded addresses - such as exchanges, or a service that receives multiple small payments - but it does ensure that an offline wallet with a huge balance won't be granted a disproportionate amount in the initial distribution.
I found this thread because I'm curious to see if any other coins have used the same distribution method since CLAM. Haven't found any yet.