Eventle - Free event management with a European twist
Eventle, a nice web tool built by Blueboard, might be a great solution for conference organizers working on a limited budget (or perhaps even a free event with zero budget). This comprises a great number of the most popular events in many cities (think of BarCamps and other, even more informal settings).
The value proposition here is quite simple; if you are running a free event you need an easy way to announce it, have the audience share the information with their friends, and hopefully get a sense of attendance so you can adjust venue or format as needed. None of those are ideal via email or [shudder] paper flyers.
To save you from endless back-and-forth emails or sheer ignorance of your attendance, a website listing confirmed attendees is crucial, and lets you focus on the planning of the actual event.
Another great option, Eventbrite, has much better name recognition than Eventle in the USA, and it is also free when used for free events.
However, I did notice one great feature Eventle alone has, an advantage borne of serving exclusively free events: the site creates a registrant queue to ensure that your attendees are as committed as possible. Sending a quick email to the registrants the day before the event will produce drop-outs, and Eventle can automatically admit and notify those behind them on the queue that they are now invited. Managing attendance becomes far easier. This feature alone, if properly used, could save many headaches.
There are a few missing features that might really help round out the experience, such as ability to host your event on custom URLs (currently you can assign a custom *.eventle.com URL). However, users looking for that branding have already paid for a URL and will likely be hosting recurring events, which means they can look into more expensive similar tools like Pathable.
For the rest, though, Eventle is a great solution - it literally provides every function we can think you'd want from a paid tool, at no cost and a fraction of the time.
[Please note: while event screenshots are from the Czech version, this software tool's website is entirely in English and allows for events in any language.]