they are great to experiment with and you can download them for freeee!
There is a web based service I am new too which provides you information on your social influence through social media sites such as twitter and facebook. It is quite a nice idea but I am not so sure how accurate it is as it doesn't take into account business people who do not use facebook or twitter. The service is called Klout and you can find it by searching on facebook its an orange logo. http://klout.com/#/GemmieV
I've also been surfing the net for useful editing websites and found one with 70 skin retouching tutorials, if you're interested you will have to fish through any not so good ones to get the the best stuff but it's a good resource to start with and you can sign up to the website newsletter also.
To get the most out of sites such as flickr, facebook, blog sites etc always return comments and make an effort to join in groups and conversations to get your work out there and increase your popularity.