If you’re still using the default download manager of Google Chrome instead of a third-party downloader such as Internet Download Manager or EagleGet, and you want it to show the download speed, you might like this one.
Download Plus adds a down arrow button on the main toolbar after installed. During download, you can click the button to check the download speed. You can also pause, resume or delete your downloads right from the Downloadplus panel. As for the deletion, the extension provides options to delete a downloaded item from the list or from the drive. The download notification flashes on the bottom right corner whenever a download is completed.
A more lightweight alternative but less functions is Downloads. It shows download speed, lets you remove a downloaded item from the list, and clear the download panel in one click.