Popular Speed Test Sites:
These sites don't give consistent results. Below are the results of 3 tests on each site at 2 AM with a linksys WRT160NL wireless-N router to a MacBook with an 802.11n wireless interface thru two walls. Site Results

speakeasy.net (Requires Flash)	20.3-23.5 Mbps
www.speedtest.net	23.3-25.4 Mbps
testmy.net [Click "Download Speed Test" then "SmarTest"]	8.0-8.6 Mbps

2011
9 PM speakeasy    6.0-13.7Mbs  speedtest.net 18-22Mbs,   


FIOS 9.8/1.8 Mbps Jan 2010
Cablevision/Optimum with boost (to 30 Mbps)
Wired (20.8-25.4) vs wirless thru 2 walls (21.8-23.8) about the same
Safari and Firefox about the same
Mar 2011
4:30 AM  20.8-25.4
10 AM 15.7-22.0
8 PM 19.2-20.0 Mbs

Info
DSLReports.com/ ranking of ISPs
reviews-zdnet.com.com/Broadband_Watch/

Bandwidth Speed Test Site List

Note: My tests showed results varied by which test service you used (20%), the media (fiber vs coax [I didn't test DSL]) (50% for some test services), depending on what computer you used (800 MHz PC vs 1GHz Mac) 60%, time of day (3-5%), and which browser you used.
e.g. IE produced the same results except for use with TestMy.net on a Mac where it was 70% slower.

Note: Speakeasy consistently found my Optimum Online (cable) download speed about 20% faster than Verizon FiOS (fiber), while Broadstar and TestMy.net found it about 15% slower. Both were around 10 Mbps download.
On the other-hand upload speeds were 20% slower for Optimum Online with Speakeasy while cable and fiber were the same for Broadstar and TestMy.net; about 1.7 Mbps.

Above tests were done on a Macintosh with OS X 10.4 and a 1 GHz G4 powerbook.
Tests done on a PC with a fresh copy of Windows 2000 on a Dell 800 MHz Pentium III produced speeds 60% slower except for SpeakEasy over verizon fiber which had speed similar to those on the Mac. SpeakEasy over cable service showed speeds 50% slower on the Dell than on the Mac.

The browser used Internet Explorer (IE), Firefox or Safari (Mac) didn't make any difference except for IE on a Mac with TestMy.net where it was 70% slower.

at&t - SBCglobal.net/dsl/speedtest/ Select location in CA, TX, IL, NY, WA, VA
      (upload & download speeds)

at&t/SBC gave results between speakeasy and test my.net on cable (10 Mbps) and very low results (1-2 Mbps) on Verizon fiber.

Browser Performance: Browser Cable fiber Mac PC Mac PC IE Firefox Safari See Also:
Network Performance
ISPs under Data Communications Interfaces