msg.value throws an exception. I don't see a way to add an ether balance to an address.
Since Solidity 4.0 you have to mark your functions with the modifier
payable in order to take Ether. This is a security measure, to avoid unwanted payments that happened often, for example with theDAO contract.
payable for functions: Allows them to receive Ether together with a call.
- from Solidity Documentation - Modifiers
When doing so, you will be able to invoking the browser-solidity transaction with an Ether charge and it will not throw an exception anymore.
Keep an eye on the current changes because Solidity is moving quickly as the entire Ethereum system does: https://github.com/ethereum/solidity/blob/develop/Changelog.md