When you at-tag a user the cursor sits at the end of that user's name. As a result, you have to hit space to successfully at-tag that person. This experience feels a little off. When you at-tag someone, what if it auto-spaced so that you can continue typing more naturally. As an example, Slack works this way.
An additional voting scheme might be very useful, especially for public challenges like ours: a basic "like" option, like Facebook, with no "dislike" to vote down. Turns out the "disagree" opportunity has gotten a little nasty in a few cases. Some people are very competitive.