jar -xvf Blah.zip

, thats how we do it at work on IBM P590 Unix servers
Theres more to life than GUI based tools you know!
why use command line I hear you ask? Well, what happens if you have 100 zip files that all need expanding, they don't even need to be in the same directory.
for file in `find . -name "*.zip`
do
echo "expanding:" $file
jar -xvf $file
done
That will search every subfolder for zip files and expand then all , you can do selective expansion by using regular expressions in the find command or just using grep/egrep
If I was doing it on a live box I'd obviously put some error checking in there and make sure that all backups are safe first!

Yes I know, sad muppet you all mutter!