Back in my ruby/rails days, I always accessed Amazon S3 from the command line. No that I'm coding in groovy/grails, I thought I would search for a groovy solution. Well, I found one, but it's not ready for prime-time. But, I did come across JetS3t, written in java with examples in groovy, so I thought I would give it a try.
After downloading, I opened the README and found that JetS3t comes with a nifty set of stand-alone and web based UI application/applets for accessing, browsing and uploading files. The application is called Cockpit and I was able to easily use it inside Firefox and as a standalone Java application.
Find out more about JetS3t suite of applications and be sure to read Andrew Glover's tutorial.