GlimmerBlocker is no longer maintained and should no longer be used as web sites have migrated from using plain http to using https (i.e. encrypted) which prohibits modification by a proxy unless you resort to install custom SSL certiticates on the client.
You should use a browser extension instead.
It was made as a hobby project during 2007-2008 by Peter Speck. It features both a custom http server and http client and a Mac OS X control panel.
GlimmerBlocker did not only block requests but also allowed for adding custom css and javascript to the pages. It also allowed for modification of the page html before the browser receives the html, which made some modifications much easier than DOM based modifications.
TinyGrab (1.01b1) can't login when a proxy is used. It sends an invalid http request to the proxy: it contains an extranous newline after the URL in the request line, before the 'HTTP/1.1'
The workaround is to add the two hosts "tinygrab.com" and "grab.by" to the exception list:
See the screen shot on the page for Norton Live Update.