Love the project. New features are key.
Here is what I would like to see:
1) proof-of-stake
There are multiple reasonable ways of doing this. Once I understand your design better, I'll suggest some simple proof-of-stake system that is compatible with your approach.
2) reduced blockchain size
What you are doing sounds great. I will be reading and thinking about your paper carefully. Don't stop here though.
3) improved wallet security
Basic idea is an account with restricted authority. You could keep the account online 24/7 without risking loss of all its coins. You would not need to mess with paper wallets under normal circumstances. This would make a hot wallet almost as safe as a bank account.
This account does the following:
a) specifies a single trusted address when it first receives coins (the address cannot be changed subsequently, address could belong to an online service provider, an offline paper wallet, a friend, whatever)
b) specifies an amount of coins, x, when it first receives coins. Account can send x coins per month (or week) to any address. Once this limit is up, further spending is not possible with one exception.
c) emergency withdrawal; account can send any amount of funds to its unique trusted address at any time.
4) zero-conf txns
I suggested something for zero-conf txns here:
http://www.reddit.com/r/CryptoCurrency/comments/1evxuk/how_toalt_coin_with_secure_zeroconf_txns/I think aaaxn must have proposed something similar. Aaaxn, what's the link for your idea again?
BTW 2864285 is cunicul keyed into a touchtone phone