My own feeling is that hashtags are everywhere, and I do mean everywhere!
For an event organizer this is a good thing, because it means that you don’t have to lecture your attendees on how to use them at your event.

For those of you who don’t know what a twitter hashtag is (no shame in that) and why you should use them at your events, here’s a quick rundown:

• The # symbol, called a hashtag, is used to mark keywords or topics in a Tweet. It was created organically by Twitter users as a way to categorize messages.
• By including a unique event hashtag in your promotions, commentary, and post-event thank yous, you’re not only pulling a conversation together, but you’re also making it easy for people to find photos and attendee interactions.

Informing your attendees of the event hashtag (pick it wisely) before and during the event is very important. You want to get the discussion going as early as possible.
But because a live tweet mainly lives on Twitter you should, as an event planner, do your best to integrate those valuable conversations into your event programme. And that’s where a Twitter Wall comes handy. It helps you to bring the tweets to the awareness of all your attendees by displaying them on a big screen during speeches and on info-screens during breaks.

There are many Twitter Wall alternatives out there. Some of them are completeley free and even open source. If you got the programming skills you can completely tailor the twitter wall to your event. The biggest drawback with the free alternatives is that they often lack the ability to moderate tweets. In general I don’t think you should moderate, and the censoring effect will be limited to your wall only (people will still be able to see the moderated tweet on their own phones/laptops/etc.). But in some cases I can see why it would be useful. Preventing some really nasty comments, for instance.

If you really care about moderation of tweets you can check out some of the paid alternatives like TweetWall or TweetWallPro.

But if you’re open minded, check out this list of the top free and open source alternatives:

Twitter Fontana

An open-source alternative for those flash based Twitter fountains, built using HTML5, CSS (SASS) and Javascript.

Website: http://twitterfontana.com/
Source Code: https://github.com/EightMedia/TwitterFontana

Twitter Fontana looks good and has a variety of animations to choose from, but lacks in customization. Settings for transition speed and number of tweets on screen would’ve been nice. On the bright side you can fork the repository on github and create your own personal Twitter Fontana just the way you want it.

Twitterwall by Remy

A conference twitter wall with built in schedule & announcements.

Source Code: https://github.com/remy/twitterwall

Twitterwall by Remy is just a source code repository and not a hosted solution like the others. This is for the event hacker who wants a starting point for creating their own wall. If you’re not a programmer you can still get it up and running using the default settings, but it will take some effort. However, the layout of the wall looks really nice and you can use it both as a twitter wall and screen for scheduled announcements and sponsor logos.

Twitterfall

Twitterfall is a Twitter client specialising in real-time tweet searches. New tweets fall into the page.

Website: http://twitterfall.com/

Twitter Fall is a great choice if you want something basic, free and without much branding. It has better customization options than the others mentioned here and can show a lot of simultaneous tweets. Twitter Fall is not only a twitter wall, but also a twitter client that you can use to post new tweets from.

Visible Tweets

Visible Tweets is a visualisation of Twitter messages designed for display in public spaces.

Website: http://visibletweets.com/

Visible Tweets is the only flash based wall in this list. You can choose from three kinds of animations where “Rotation” is my favorite. The background color of the wall changes as you rotate through the tweets. The public version of Visible Tweets is limited by Twitter’s data restrictions. Meaning it only fetches new tweets every 5 minutes. A very good thing about Visible Tweets is that it has no branding at all in fullscreen mode.

My naughty trick to getting rid of Twitter Wall branding messages

Since you’ve taken the time to scroll through this whole list, I’m going to tell you a dirty little secret that you can use to remove the branding from the HTML5 based Twitter walls in this list:

If you have FireFox or Chrome installed you can right click on the branding, select Inspect Element and then press “Delete” on your keyboard.

If you do this correctly you should be able to use Twitter Fontana or Twitter Fall without displaying their logos and branding text. As long as you give something back to the developers like donating a couple of Pounds(TwitterFall) or Bitcoins(Twitter Fontana) or sharing their work, I think they’d be cool with that.