DownTester is a portable app that tests download speeds from HTTP and FTP URLs. It's unobtrusive and gets the job done, but also comes with some useful features that make it worth downloading.
The Advanced Options menu is reasonably robust. You can configure the tests to conclude and move on to the next URL based on time or bytes downloaded. Both of these are user configurable, giving the test broad powers to judge how fast data is flowing to you. You can also set the program to retry upon failure and configure the number of times that repetition should occur before moving on. FTP addresses can be tested in Passive or Active mode. Users have the option to export their test list by saving it as a TXT, HTML, CSV, or XML file, and there's an import test list option as well--Add URLs from File. You can even toggle test URLs from an existing list.
As simple as it is, DownTester didn't seem to need much fine-tuning. You can't paste directly from the clipboard to the test list; you first have to open the Add URLs List window, but that seemed to be just about the only drawback to this utility. Anyone who is trying to diagnose connection speed problems should check it out.