Are there any easy to use GUI's for Ethereum?
Yes, the Meteor DApp wallet which provides a decentralized app which allows you to manage accounts, simple wallets, multisignature wallets and smart contracts on top of an eth/geth node.
Currently, there are binary releases available by the mist browser developers who bundled them into a nice clickable executable, called "Ethereum Wallet". Downloads here.
In addition, there is the AlethZero C++ client, the so called hardcore client. (Not in the category easy-to-use but offers a GUI.)
The MIX IDE is targeted at developers of smart contracts, rather than end-users, it is also not easy to use, but it also allows you to interact with the blockchain by utilizing the GUI.
IDE is the leading development tool today, currently in private beta.
Can be seen as demo here: https://www.youtube.com/watch?v=xbZjMFycSrs
Ethereum Wallet (Mist) is currently in beta. https://github.com/ethereum/mist/releases