Your personal website i think is great! You can set up your page however you like and you can add as many tabs and links to it as you like. you can put whatever whenever you like and however you want. The greatest thing about this is that they have websites and companies that make it easy for you to set up a page (weebly) and they also have upgrades and other companies that have monthly or yearly fees to pay for a specific domain. The downside to this is that anyone with internet and a device to log on can go to your page and look at it as it is open to the world to see. So in a way you might want to keep some things back when putting things on your page.
Linkedin is a great place to make your professional portfolio stand out. as in my experiences it is mainly to enhance your professional presence instead of the likes of facebook. Linkedin helps you connect with old and new colleagues as well as potential ones. I like to think of it as one of my classmates mentioned it "facebook with a suit and tie" because it is a way to connect but professionaly. You can add pictures and links and people can like or comment whatever you put. Some of the bad things i found with Linkedin is that yes it is free but the free account limits you to certain things you can do and you have to upgrade to get more features. Also some people can log on and put negative content with you and you can possibly get a bad rep from some one who dislikes you. Or of somthing you have posted and a potential employer may see it and take things a bad way. But all in all Linked in is a green light for me!
Plaxo is fairly new to me. I only heard about it recently and if you look at the bigger bigger and what its meant for. I believe it is a great tool to stay connected with people. How i understood plaxo is that its one big datatbase where it gets all of your contacts information from different areas and syncs it and puts it together and it is constantly updating as people have changed their info. The downside to this is that everyone changes information and it could be tricky and you are getting information from many different areas. Also if you wanted to upgrade it does cost money.