Free screen grabber for OS X
If you have ssh access to some server, you might use a script like this:

f=$(date +%Y%m%d%H%M%S).png
screencapture -i ~/Sites/upload/$f
printf %s http://example.com/$f|pbcopy
scp ~/Sites/upload/$f user@host:public_html


To make scp not require a password, run ssh-keygen, accept the defaults in every step, and then run ssh user@host 'mkdir -p ~/.ssh/;chmod 700 ~/.ssh/;cat&gt;&gt;~/.ssh/authorized_keys;chmod 600 ~/.ssh/authorized_keys'&lt;~/.ssh/id_rsa.pub.