I would immagine that CNET"s downloads are fairly accurate as far as statistics go. They aquired Download.com some time ago, and it has always been one of the (if not the) top destinations to download stuff from the web.
Adobe Acrobat would be hard for any site to judge how many times it was downloaded. Most of the time when there is a website that has a PDF, then the browser will just install it as a plugin.helper. Then the average user will have a PDF open up in their browser if they open a local PDF.
As for ICQ, I was one of the first 1,000 or so to download and use it. My old ICQ# was 10359, (I think the numbers started at 10000, but I am not positeve about this...) but somehow my account was compromised about 4 years ago and I lost the number I still use ICQ to this day, and refuse to use AOL/Yahoo. ICQ is a very small client, that dosen't serve up ads, and dosent take up to mych landscape on the screen ect.. Plus it's free of all the crap that comes with many IM programs now, with a feature to not accept messages unless they are from someone in your buddy list. You can also send messages while someone is offline, and will be received when they logon to the net.
Going back to download sites, if you guys have not checked out http://www.snapfiles.com, it is a GREAT download site! They have a shareware & a freeware area. Most of the time if I am looking for some sort of utility ect, I find it in the freeware section. The files are rated, and it is a really clean listing with descriptions to look through for stuff. I highly reccomend it!