What are some alternatives?
When comparing GrabIt and GetNZB, you can also consider the following products
SABnzbd - SABnzbd is a free/open-source cross-platform binary newsreader written in Python.
NewsBin - NewsBin Pro is a Usenet NNTP newsreader that downloads and decodes binary file attachments to...
HelloNzb - HelloNzb - The Binary Usenet Tool
NZBGet - The most efficient usenet downloader.
alt.binz - alt.binz is a powerful binary newsreader, for downloading and managing articles from Usenet.
Nzbvortex - The small and efficient NZB client for OSX, optimized for performance and ease of use.