This is a nonflash-based internet speed test site. It measures your real download/upload/mixed-test speeds using varying amounts of data. It also "gets smarter the more you use it and makes adjustments specific to your computer for a high level of accuracy." I would like it better if it improved my download speed so that it matched my ISP's advertised speed rating.
I've taken 3 tests and so far the results are accurate concerning the file download speeds I've recorded in the past. I haven't tested on youtube's speed test since I changed ISPs.
On an ISP-advertised 50 Mbps connection, I'm really getting 7.3 Mbps or 914 kB/s. But my browser has measured over 1000 KB/s on some downloads like windows updates.