Last month [1] I heard a rumor that it was possible to find out the resolution of a browser window and I found no proof of it. Well, I was wrong.
I wasn't entirely wrong, but via SlashDot, [2] a report on Earthlink's [3] browser that does include that information. I checked my own log files and yup, there it is:
Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::000041100400030003e201f6000000000501000900000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::000041100400030003e201f6000000000501000900000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::000041100400030003e201f6000000000501000900000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::00004110028001e002740103000000000502000800000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::00004110028001e002740103000000000502000800000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::00004110028001e002740103000000000502000800000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::00004110028001e002740103000000000502000800000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::0000411003200258029a015b000000000503002a00000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::0000411003200258029a015b000000000503002a00000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::0000411003200258029a015b000000000503002a00000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::0000411003200258029a015b000000000503002a00000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::0000411003200258029a015b000000000503002a00000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::0000411003200258029a015b000000000503002a00000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::0000411003200258029a015b000000000503002a00000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::0000411003200258029a015b000000000503002a00000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::0000411003200258029a015b000000000503002a00000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::0000411003200258029a015b000000000503002a00000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::000081100400030000000000000000000503002a00000000 > Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) > ::ELNSB50::000081100400030000000000000000000503002a00000000
Also from the logs, it looks like they started using this on or about April of 2000, so it's been going on for some time now.
[2] http://slashdot.org/article.pl?sid=01/03/20/1423223&mode=flat