We are having

We are having an event in a few months and want participants at the event to be able to tweet their experience with a hashtag and have those posts automatically go up on a social wall on our website.

I have seen a couple services that are monthly subscriptions, but this is more of an annual thing. Looking for a plugin solution that would take tweets with specific hashtags or posts to a specific Facebook page and combine them on a social wall page that has a gallery of slider operation of the posts.

Any ideas will be greatly appreciated.