You can vote on each of these websites every day.
When the total monthly votes for the server passes a certain amount of votes, then every player on the server will get a reward.
With 25, 50 and 75 votes everyone gets a Poking Stick.
This is a stick with level 10 knockback.
This gets more hits with every vote milestone.
And with 100 votes everyone also gets a special Fire Armor set.
Click on the picture of the website to go to it.