access log question (referrer hiding?)

[CTho9305]

I see a lot of stuff like this in my log:

24.66.86.126 - - [15/Nov/2003:14:35:51 -0500] "GET /pics/funny/coolnumb.jpg HTTP/1.1" 200 15011 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)"
82.139.197.148 - - [15/Nov/2003:15:03:06 -0500] "GET /pics/funny/coolnumb.jpg HTTP/1.1" 200 15011 "-" "Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.6a) Gecko/20031102 Firebird/0.7+ (aebrahim)"
81.14.145.32 - - [15/Nov/2003:20:19:03 -0500] "GET /pics/funny/coolnumb.jpg HTTP/1.1" 200 15011 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)"
217.80.65.46 - - [15/Nov/2003:23:12:47 -0500] "GET /pics/funny/coolnumb.jpg HTTP/1.1" 200 15011 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; Crazy Browser 1.0.5)"
217.80.65.46 - - [15/Nov/2003:23:12:48 -0500] "GET /pics/funny/coolnumb.jpg HTTP/1.1" 200 15011 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; Crazy Browser 1.0.5)"
217.80.65.46 - - [15/Nov/2003:23:12:46 -0500] "GET /pics/funny/coolnumb.jpg HTTP/1.1" 200 15011 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; Crazy Browser 1.0.5)"
80.134.240.254 - - [16/Nov/2003:02:27:49 -0500] "GET /pics/funny/coolnumb.jpg HTTP/1.1" 200 15011 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)"

The list of accesses goes on, the vast majority without referrers. Is the other site using some trick to get the browsers not to send a referrer header? (I don't care if people leech as long as they keep it under 1gb/day )