Adventure Lobbies is a free service for Minecraft that lets you invite your friends to play popular adventure maps with you.
Setting up a server can be a hassle. On average, it can take up to a couple hours for an in-experienced user to setup a server to play with their friends, and even then, the majority of people don't even keep the server running very long.
On top of the effort required to make your own server, most ISPs (Internet Service Providers) cap the amount of bandwidth you can use to a relatively low amount. For such a bandwidth-intesive game, this means that just by playing maps with your friends using your home computer, you could get fined by your ISP for up to a couple thousand dollars!
The best part about Adventure Lobbies is that it is a free, lagless, 24/7 service that has over 70 different popular adventure maps and even the ability to generate your own world with a custom seed. All lobbies run for up to a duration of 7 hours, which is plenty of time to get everything done.
All maps provided by Adventure Lobbies are approved by the map creators and suggested by the community. Each map has been tested to work and is configured to the proper difficulty, restrictions, and comes with downloadable notes/instructions that may be vital to the story line.
I've gone into the smallest of details such as: the ability for Enderman to pick up blocks, limiting certain mobs from spawning, forcing daylight/night, weather, monsters/animals, and more for the most ideal gaming experience.
* For legal reasons, maps are not downloadable at any point through this service, and must be played on the server for the time it is run for.