Glasflow is an extremely small app that shows the network speed as an icon in the status bar.
It does one thing and aims to do it well without any excessive bloat. Glasflow has a minimal memory footprint and is primarily active while the screen is on.
For more information and screenshots, visit the Play store: https://play.google.com/store/apps/details?id=com.mridang.speedo
The notification icons used for this app can be genrated using this Gist: https://gist.github.com/mridang/56839354d76be8bacaea