Someone asked me today, I've installed Ubuntu 10.04, is there anything else I need to do? I somehow manage to end up building a new Ubuntu based machine almost every week, and managed to memorise my perfect setup. This is by no means a must do, but something to think about. A few of these will help your security but others might just enhance the experience. I'm going to be coming at these at more of a desktop angle, I shall prepare an Ubuntu Server list very soon.
Enable 3D desktop effects
If your a desktop user and you have a nice graphics card this is a must. In my office we call this "jelly windows", but it's more than that. If you've got the graphics power then you'll be a fool not to turn on the advanced desktop features in the Appearance Preference.
Setup missing codecs
Ubuntu 10.04 comes bundled with a few different media players, but these aren't very good if you don't have the codecs to play those songs you purchased from Amazon on your Windows install, luckily if your using Ubuntu to look at this post right now just click here and these packages will install using APT (ubuntu's built in software manager) Simple huh?
While your finding your way around Ubuntu you might fun simple utilities missing which you used everyday on other operating systems, there is a good chance these features are there. During this transion period I used Webmin, which is a web based service which lets you do pretty much anything on your new Ubuntu install remotely via a website, the main perpose of Webmin is clearly for remote admin, But if your into your Linux and you know your way around a little give this a shot, it's a simple deb install from Webmins site. Just download and double click to install the package.
I'm a massive dropbox user, and since signing up I've ditched my pendrive. As I also use a Mac I was getting messages almost monthly about signing up for the MobileMe account, but resisted because of the yearly cost. Ubuntu 10.04 has a built in option called Ubuntu Once, which once you've signed up will give you 2GB of free storage to play with. You can also tie this into your firefox bookmarks, contacts, notes, calendar items, etc, on every Ubuntu machine you own. Nice.