Grokker seems to be beset by some of the most malicious and uninformed reviews I have seen on Versiontracker.

• Yes, this is a Java app.
• No, it has not been fully "Cocoaized", so that look and feel (including the install process) are not particularly Mac-like.
• However, the interface is perfectly clean, clear and functional.

I have been using this product since the very first Mac beta version, and have yet to run into any major difficulties with it, or any problems with customer support - wish I could say that of all my apps...
Most importantly, what this application does - organize search results into categorized graphs - is unbelievably useful if your work depends upon heavy search engine use. My recommendation: pay no attention to the naysayers and give Grokker a shot - you might find you like it.