There are many reasons why you could want to put a link to other websites on your own. For instance, your friend is a photographer and he took all of your headshots. Wouldn't it be nice to add a link to acknowledge his excellent work?
It may not be wise to share your political views on your professional website, but everybody has something that they believe in. Why not add a link to a charity that you support to show that you care.
And how about your other websites and profiles? Personal Facebook pages may not be the greatest idea here, but as far as social pages are concerned, LinkedIn and your IMDB profile are highly recommended. Did not have time to upload all of your photos into your website yet - how about adding a link to your Flickr, Picasa or Instagram? Do you have a relevant blog? Maybe one that follows your struggles and successes as a professional actor? That's great - let the world know about it.