I don't know, as a recent arrival from Java I sure miss my IDE. - Having a background parser running all the time means I never save a file with a syntax error. - It's totally silly that I have to type method names for things like File and IO and so on, the system should guess them for me - Refactoring! I find that I want to change the names of classes and fields and methods quite often, and having the IDE do it is a big time-saver. - In NetBeans there's this window on the side (I'm sure Eclipse has the same thing) called the "Navigator", which is just a list of all the methods and fields in the file you're editing, you click on any of them to go there; huge time-saver. - One-click to run the tests for whatever the cursor's on - One-click to find all usages of whatever the cursor's on - One-click to open the docs for whatever the cursor's on - scope-sensitive select. Expand scope to current block, next enclosing scope, next, next, etc Yeah, you can do something in Ruby in a third the lines of code that Java would take. But you might be able to write the Java about as fast, with a good IDE. [Oh, btw, I know that dynamic typing makes some of these things a lot harder than for statically-typed languages like Java. Doesn't mean they wouldn't be helpful.] -Tim