Background
After my initial end user introduction to CRM, I found that CRM provides great User Interface customization and you may know about this. You can add tabs, sections, IFRAME, fields so that you're not bound to displaying a field at a specific place in a form.
In particular, IFRAME is great as any external page can be presented in it without browsing elsewhere or opening a new window, and SharePoint page is no exception. After providing URL to SharePoint site for an IFRAME, I realized that some of UI components on SharePoint page distract users. For example, SharePoint's top navigation bar is not required if you do not expect users to navigate much. Similarly Welcome menu in SharePoint displays current user name that is already available in top-right corner of CRM page!
Such extra components on SharePoint page not only provide more (and probably unnecessary) info. than users need but also add annoying scrollbars to IFRAME. Fortunately there is an easy solution to this...
SharePoint Designer 2007
It is a great tool to customize SharePoint pages, sites without writing single line of code! I carefully customized SharePoint UI so that it looks good from CRM's IFRAME and fits with CRM UI. At high level, I updated SharePoint site's master page, removed unwanted components (without breaking SharePoint, of course!), re-structured a little bit and saved my changes! Each of this can be explained in great detail but that is beyond this post!
To learn more on SharePoint Designer 2007, visit SharePoint Designer 2007 home page
CRM now displays SharePoint sites (documents for each account, client for example) very nicely!