Simple Poll - The easiest way to create polls in Slack
Three Cents - Quickly create polls and gather opinions from anyone
Curious Polls - Answer a question once a day for the chance to win £100/$100
RankedVote.co - Embed ranked-choice polls and contests on your site.
Twitter Polls - Polls embedded in tweets
ViceVersa - ViceVersa does File Synchronization, File Replication, File Backup and File Comparison.