Start a Blog
Take soe pictures of really silly faces or subject matter and post them on Facebook
Play Scrabble Online with a stranger
Go to discoverfun.com and read the list of 500 fun things to do
Go to the google translator on the internet and translate insults into different languages
Go web shopping for odd unique tshirts
Go check out some online casino action
Make a webpage, or, better yet, make a webpage about how cool having fun is
Search the net for instructions on how to make an origami tomato, hippo, baby carriage, or whatever comes to mind and attempt to make it.
Search your own name on the web - see what you find - if you find others with the same name email them and say hi.
See if you can make $25 selling something on Ebay
Find a place and organization that you might be interested in volunteering for and then request they mail you some information.
Sign up for an online dating service
Sign up online for discount cards for merchants with a crazy name like Larry HuffelDuffelBum
Surf the web
Take polls on the web and try to give the worst possible answers
Write music on a music composition program and post it on icompositions.com
Watch a video on Ted.com and expand your mind
Make your own online to do list....rememberthemilk.com
Map your thoughts at bubbl.us
Watch the best photos of the last seven days from Flickr
Sharpen your brain power at GamesfortheBrain.com
Start a group on Facebook that is dedicated to Fun or Funny Pranks
Start a fun album of photos on Pinterest