[BTC+Altcoins] What about a 2-tiered mining fee? Like Dwolla pricing.

[manicminer]

Do we have a list of determining the recommended mining fees for various amounts in various coins? Fair fee, instant delivery.

I really like this (the fee structure):
"The most simple pricing, ever."
https://www.dwolla.com/fees

No unreasonable fee for small transactions, fair simple fee for larger transactions. Instant delivery.

See also: http://www.quora.com/Dwolla/Does-Dwolla-prevent-users-from-structuring-payments-to-evade-the-0-25-fee

[anti-scam]

This is how it already works, but the determinant of "transaction size" is not the amount of coins transferred (which has no real relevance to the network as a whole) but rather the size (in kilobytes) of the transaction. Unfortunately decentralized storage is not cheap. Storing a transaction that transfers 0.00001 coins can cost the network just as much as one that transfers 500 coins.