You can use HAProxy for load balancing, there are articles about it here:
https://digitalocean.com/community/articles/an-introduction-to-haproxy-and-load-balancing-concepts
here:
https://digitalocean.com/community/articles/how-to-use-haproxy-to-set-up-mysql-load-balancing--3
and here:
https://digitalocean.com/community/articles/how-to-use-haproxy-as-a-layer-4-load-balancer-for-wordpress-application-servers-on-ubuntu-14-04

With a single HAProxy node, this woulds still leave a single point of failure. Since DO doesn't support floating IPs (yet) you can't scale this up to having 2 geodiverse HAProxy nodes. That said, it's still an improvement over round robin since an app node is far more likely to go down than a slim, hardened HAProxy node.

You can also use nginx for load balancing (this is quite popular these days):
https://digitalocean.com/community/articles/how-to-set-up-nginx-load-balancing

nginx will have the same issue that HAProxy does, in that you still have a single point of failure.

Since DO doesn't support floating IPs (yet), I'll mention Amazon's Route 53 which is capable of intelligent round robin, health checking destination nodes, and geo-diverse hosted DNS, it's also relatively cheap:
http://docs.aws.amazon.com/Route53/latest/DeveloperGuide/Tutorials.html

You can use Route 53 in conjunction with DO droplets. I believe DO is working on their own implementation of floating IPs to solve the super high availability problem.