A colleague pointed me to the Canadian Language Benchmark's Online self-evaulation site. If you're on a mac, you won't even get past the splash screen, which appears broken, but on windows with Explorer, you should be OK.
I found no stats about reliability, etc. But it appeared to be a reasonably well-designed test of reading and listening skills. I only tried the English version, but I assume there's also a French version. Off the top of my head, I would say the questions range from CEFRL level A1 to B1, or perhaps B2 with most being in the lower part of that range. There is nothing particularly difficult.
It appears that the site is still in Beta. Some problems I noticed:
It runs only on Microsoft Windows in the MS Explorer browser with Active-X turned on. Most computers have Active-X turned off by default for safety reasons. There is a small message at the top of the screen asking you if you want to turn it on, but it's not obvious. So, for most users, it will appear that the test doesn't work, even though in fact, it should be OK if they notice the alert. It will not run on Mac or other OSs.
The feedback is not specific. After I went through a test, making errors here and there as I tried to mimic student behaviour, it told me I was at CLB level 7, 8, or 9, quite a range. No information was obviously available about what that meant, nor was any feedback given on the relative strengths and weaknesses of my reading versus my listening. No item-by-item feedback on what I answered correctly and incorrectly was available, nor was a total of how many questions were answered correctly.
Halfway through the test, their server seemed to take a holiday for about 3 minutes. This was after I had spent about 20 minutes on listening questions. Most users would have little idea how to carry on at that point, but I managed to get back on track without my session data being obviously lost.
I'll be adding this to my list of free online self assessment tools.