Simple solidity membership contract

membership.sol

pragma solidity ^0.4.9;

contract Organization {
    struct Member { // Struct
	    string nickname;
		string city;
		bool active; 
	}
	mapping(address=>Member) public members;
	uint256 public fee;
	
	function Organization(uint256 _fee) {
		fee = _fee;
	}

	function register(string _nickname, string _city) payable {
		if(msg.value == fee){
			members[msg.sender] = Member( {
				nickname: _nickname,
				city: _city,
				active: true
			});
		} else {
			throw;
		}
	}
}

interesting