This 3 part post series discusses how you would go about
customizing the user profile page accessed from the "My Settings"
link in the welcome menu.
That's this page here:

Although it seems like a simple task, there is actually quite a
lot to consider. I am also planning to demonstrate a number of
useful SharePoint techniques along the way.
The first part is about application pages in general and why
they cause headaches for designers trying to customize the look and
feel of SharePoint.
Application Pages
One of the first things people want to do after installing
SharePoint - is to make it look like anything but SharePoint.
If you have ever been involved in skinning a SharePoint/WSS site
you will know the difficulties posed by application pages. These
are the pages in the "_layouts" directory that are shared across
all SharePoint sites. It is always recommended to NOT edit these
files as all web applications will be affected by the changes.
This is not a problem for most application pages as they are
generally only accessed by site administrators. There are however a
few application pages that are viewable by all users. It can be
very frustrating to find that after you have gone to all the
trouble of skinning a SharePoint site only to find that a few pages
still render that standard SharePoint blue.
Two commonly problematic pages are:
UserDisp.aspx
This is the user profile page shown in the above screenshot, it
links to a number of other application pages such as UserEdit.aspx.
The page is accessible by any authenticated user. It is also the
focus of this post series.
SearchResults.aspx
The standard WSS search page. In MOSS there is also the
osssearchresults.aspx page for the standard "This List" and "This
Site" search scopes.
There are a few techniques that can be used to customize these
pages. The easiest way would be to simply manipulate the pages in
the LAYOUTS directory. Obviously any changes made are going to
affect all your SharePoint sites.
It also presents a problem during deployment, how are these
changes going to be packaged up to make releases easy? What if
there are multiple front end servers? And what happens when a
service pack comes out that has new versions of these pages? Its
probable that your changes will be overwritten.
Luckily the creators of SharePoint had foreseen these issues and
in most cases have provided a way to customize these pages safely.
More about this in Part 2.
Part 2 will demonstrate how we can manipulate the My Settings
Link