|a photo I took at the RedBull crashed ice event recently,|
edited with the cartoon effect on FotoFlexer
You can upload a photo straight from your computer.
This website makes editing Facebook photos easy too, just grab the URL. There's even the option to sign in through Facebook.
Other services offer integration as well:
They've covered most everything you could want in an online photo editor and it is free :)
There isn't much else I can say - other than go play around with the buttons. Then come back and let me know what you think.