Twitter Polls - Polls embedded in tweets
Cvent - Cvent's event management software provides event planners with a complete solution to increase event attendance and decrease event costs.
Simple Poll - The easiest way to create polls in Slack
Eventzilla - Eventzilla lets you sell tickets online and manage attendees from one integrated application.
Curious Polls - Answer a question once a day for the chance to win £100/$100
Attendify - Develop relationships at the events that you attend by creating smaller events with just a few people.