My access_log shows that I am getting slammed with random get requests like:

61.139.105.163 - - [20/Oct/2008:08:53:44 -0400] "GET http://ad.yieldmanager.com\
/imp?z=0&Z=0x0&s=322680&y=30 HTTP/1.1" 302 - "http%3A%2F%2Fwww.tomflashgames.co\
m%2Findex.html" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; MyIE2; Tenc\
entT"
host194.190-136-123.telecom.net.ar - - [20/Oct/2008:08:53:45 -0400] "CONNECT 20\
0.80.42.159:25 HTTP/1.0" 404 673
host194.190-136-123.telecom.net.ar - - [20/Oct/2008:08:53:45 -0400] "CONNECT 20\
0.80.42.159:25 HTTP/1.0" 404 673 "-" "-"
61.139.105.163 - - [20/Oct/2008:08:53:56 -0400] "GET http://ad.yieldmanager.com\
/imp?z=0&Z=0x0&s=322680&y=30&B=1 HTTP/1.1" 200 6612

My domain is blabrag.com. However, these requests are slowing down my computer. Any idea of how to avoid/filter these requests?

Well it turns out that I enabled a full proxy server with mod_proxy unintentionally. This some how put me on a proxy list and people from around the world were trying to use my server as a proxy. As a result, I created a default virtualhost to handle all the invalid proxy requests. We will see if the traffic dies down .