Goo.im used to be a file hosting for Android and GooManager is the app with which we could download ROMs, APKs, kernels and all sorts of files hosted on that service.
Access to a huge repository of Android resources
As you can imagine, it was an application conceived for advanced Android users. In other words, if you didn't need to do anything else other than downloading and installing apps on your smartphone or tablet, you would have never found it useful. However, if you needed to download a new ROM for your Android, here you could find an important repository full of resources that you could explore from the app.
But although we can no longer download them because the website has stopped operating, it does allow us to run a Reboot Recovery on our device and flash it with a new ROM if we've already downloaded from somewhere else. Therefore, it can still be somewhat useful, especially if we intend to root our smartphone to gain superuser permissions.