Do you know any good smalltalk implementations which meet the following criteria:
I'm asking this because I heard a lot about smalltalk, and I want to learn it - just for fun. But it seems to be hard to find the right tools and books for this language.
I am happy developing commercial web applications on a Mac in Pharo. Cross-platform development is easy and painless. I work together with a Windows-based developer and we deploy on Ubuntu. There we use the commercial Gemstone system (OODB) in its free version. We use Monticello as a distributed version control system. I've taught a student the basics of smalltallk and Seaside with James Foster's tutorial. A more in-depth explanation is in the Seaside book
When creating domain models, Glamour is a fantastic toolkit to create browsers, allowing the navigation and visualization of the model. It is part of Moose, a software reengineering system, also based on Pharo.
There are of course also weaknesses: Pharo changes a lot. Track the changes that are going on on the issue tracker and the mailing list. Staying about a month behind the bleeding edge is about right for us. Integration with legacy systems is easiest with REST web services or files. Smalltalk tends to use a lot less XML (SOAP) than .NET and java. There is no good 64 bit support. There are 64 bit images, but they have not been tested enough and are known to have problems.