When designing a portal, keep the major areas in mind in relation to your URLs. SharePoint allows 20 areas (one being the Home) to be formatted nicely in the URL. For example, http://ThePortal.com/HR or http://ThePortal.com/Training. Once you hit the end of your 20 allotted areas, the URL will start organizing the areas into buckets. For example, http://ThePortal.com/C1/Helpdesk (note the C1).
Knowing this going into your Portal planning will help you better meet the needs of your major areas (and their respective content owners). What you don’t want to do is create an area, and all sub areas underneath it, then move on to the next area. You will quickly run out of your 20 clean URLs. Instead create your all your major areas, and then if you foresee a need to use one in the future, create a dummy area to hold it’s place. Then when you need that area, delete your dummy area and create the new one. Deleting an area in that set of 20 will automatically give the clean URL to the next area created.