An update to the Ubuntu 11.04 installer (Ubiquity) finally brings upgrade support to the Ubuntu Live CD. That means that for instance if you use Ubuntu 10.10, when you'll boot the Ubuntu 11.04 Live CD you'll have an option to upgrade (without losing your documents and installed applications). Besides this change, there's also a redesigned partitioner:
GParted is a partition manager you can use to resize, copy or move partition without losing your data.
The latest GParted 0.8, released a couple of days ago, adds an option to rescue data from lost partitions:
multicd.sh is a shell script designed to build a multiboot CD / DVD image containing many different Linux distributions and/or utilities. You can use it for instance to burn Gparted Live, Clonezilla and Ubuntu, all on the same multiboot DVD.
This a great how-to that gives you step by step instructions on how to create a custom Ubuntu live disc (of any flavour). The artical is a bit old (it refers to a flight cd for dapper) but the method is still the same for the latest release.