Partiton Magic "should" do what you want, it does work with ext3 not just ext2. Ive used it before to resize & move linux partitions with out any problems, so you should be fine.

I have some USBFDs here on which I have live distribs. Is there a tool similar to Partition Magic (Windows) which allows you to dynamically enlarge Linux and related partitions on a USBFD without ...

In my first post on this subject, Btrfs basics, I discussed how to create a simple btrfs filesystem, or a complete btrfs Linux system. The information and examples in that post are going to be ...