Which 'system' apps can be safely removed

I’m not sure why you would want to remove any of the apps that you mentioned — it’s not like they take up a lot of space or introduce security vulnerabilities or anything.

On the other hand, it would make sense to remove e.g. Java, for the reasons I mentioned before. If you don’t need Java, you can remove it by following these steps.

First of all you need to check which JVM (Java Virtual Machine) you have in your system. To do so, open Terminal.app, and enter:

sudo /usr/libexec/java_home –xml

If you you have JVM installed, you’ll get the JVMHomePath returned:

/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home

Then, remove JVM from your system:

# Wipe out the JVM installation location
sudo rm -rfv /System/Library/Java

After this, restart your Mac, and confirm JVM was successfully removed by running the first command again:

sudo /usr/libexec/java_home –xml

It should say something like:

Unable to find any JVMs matching version "(null)".
No Java runtime present, try –request to install.

This means that it worked, and that your OS X Lion is Java-free again.

_{(This is an improved version of the instructions on http://stikine.wordpress.com/2012/03/02/howto-remove-java/.)}