I'd like to implement a reliable data feed in a solidity based crowdfunding contract. the goal is to collect a certain amount of ether that equals an euro amount at the end of the funding. Is there a gateway or feed system for ethereum yet?
Edmund Edgar from Reality Keys here.
Reality Keys provides signed data for ETH vs Euro (and various other currencies) which you can feed into a smart contract.
The Eth price is coming from Poloniex, but these feeds are actively maintained rather than just making the data source the final word, so if the Poloniex API changes or goes away we can substitute a different data source and your contract will still work.
you can use smartcontract.com to use any API (JSON) as the source of an oracle, so from there you can use it in any smart contract on ethereum network.
Not sure about your specific use case, but have a look at http://microtick.com. The goal is to have a trustless data feed for Ethereum (for continuous data, i.e. free running - not a prediction market)