Anyone who uses events, either online or offline for demand generation or inbound marketing will likely suffer from the same challenge - all the effort you put into promoting the event and driving registrants gets diminished by half on event day as 50% of your registrants forget to show up. 

There are numerous reasons for this, but let's look at them one at a time. Just plain forgetting is one of the common reasons, made even more common if you don't do everything possible to ensure your prospects are able to remember.

In the email editor, click the Insert/Edit Hyperlink button, which pops up the Insert Hyperlink dialog box. Instead of inserting a normal hyperlink though, change the action to "Open an ICS Calendar file". That provides a standard Calendar file that will work with Outlook or whatever desktop email/calendar program they happen to be using.

In the Calendar Entry section, be sure to add in any online event details for your web conferencing provider for the meeting so your attendees have quick and easy access to the information they'll need to join.
The second way to create the ICS file is to have it automatically created from an existing event in the Eloqua Event module. Once your familiar with using ICS files, you'll be able to create one from an event in a similar manner to how we've created it manually here.

Nothing beats a great speaker and compelling, original content for driving attendance at a webinar or seminar, but the more you can help your registrants to remember the details of the event, the better your ratio of registrants to attendees will be.