Everything! I've been using Springloops for about 7 or 8 years now for managing development projects in 4 different companies and private work and it keeps getting better.
If I had to pick the feature I like best it's the deployment. I choose the branch I want to deploy, press the button and it's sent to my server. If there is a bug I can roll back just as easily.
AND... it's free. I have paid accounts for work but for private stuff where I only need 1 project at a time I can easily use use the free tier.
Managing and deploying source code online. Tracking bugs and feature requests.
There are a lot of hosted code repositories out there that will host your GIT or SVN repository for you. Springloops has 2 major advantages over the rest:
Firstly - It integrates deployment via FTP so you just add the server you want the code deployed once to then whenever you want to update the server choose the version and hit the button. You can have more than 1 server too so if you've got a test server you can get it to deploy new code as soon as it is pushed to the repository or if you have load balanced servers you can deploy to them all at the same time.
Secondly - It integrates tasks, time management and a Wiki into the same platform so you can keep everything together in the same place in a single project.