I just came to know from my colleague about XML Spy’s Eclipse integration. XML Spy is probably the best tool for working with XML. But I always prefer working with XML from within Eclipse. I used XMLBuddy till now. It is a nice plugin but has a modest feature set when compared to XML Spy.
Now I can get all the benefits of XML Spy from with in Eclipse. The integration seems refined and all the features of XML Spy standalone product is available in Eclipse. The Eclipse integration plugins is available in the here. Both Eclipse and XML Spy must be installed first before installing the integration.

Plugin for XMLSpy Professional is here http://www.altova.com/download_spy_professional.html
Plugin for XMLSpy Enterprise is here http://www.altova.com/download_spy_enterprise.html
XMLSpy is a decent product, but the pricing scheme is outrageous. This company is not a friend of the open source community. The only product that you can get from them without paying one of their ridiculous fees is uselessly crippled.
How much did you pay for your XML Spy license?
The home edition is free…
Features, ok. But XMLBuddy has an XML Schema validator that works. ;-}