I'm often asked by new Linux (Ubuntu) users what things I do immediately after installing Ubuntu; to tweak it a bit more. Here's the answers for the 10 things I do to customize a new Ubuntu Hardy installation:

1) sudo aptitude install sbackup

Nothing is worse that losing all your important data (pictures, email messages, music, documents, etc.) The above command will install Simple Backup Suite (more details found on Sourceforge). For me at least it's a great desktop backup solution. I can select which directories I want backed up (full and incremental), then have backups automatically transfered to my external network storage. I play a lot with my computer, I often break something as a result. With sbackup, I can be more confident as it's easy to restore data (in the event I have to reinstall an application or even worse... the OS itself).

2) sudo aptitude install ubuntu-restricted-extras && sudo aptitude install w64codecs

If you enjoy music, videos, and so forth, you'll want to install the extra media codecs and packages that will allow you to play almost any desktop media format.

rest here