Remote jobs are much more common than you may think. A lot of it depends on your experience level and the type of job itself. Remote developer positions are much more common than remote admin positions for very good reasons. Admin roles tend to require user interaction and training of users. How can you do "admin by walking around" if you're not on site? Ditto for helping with user adoption? So when it comes to admin work, it greatly depends on the maturity of the org and what they want done.
As a developer, I've worked with clients all over the country. I've also interviewed for a number of permanent or long-term 1099 positions. I found some of those through word of mouth while many others were advertised in the Success Community in the Job Postings Group owned by @DanielHoechst which I help moderate. There's another fairly new Group on Success Community called Remote Jobs along with the SFDC Developers Group where remote jobs will be listed. You'll find positions advertised in the Developer Forum's Job Board.
Sites I'm aware of outside the Salesforce ecosystem include CrmMarket, Virtual Vocations, the Hired on Demand Jobs Board and Guru, the latter of which is mostly for freelancers. Be aware that the fact you're located outside the US, even if you're legally able to work in the US, could easily be an issue for some who might otherwise hire you remotely. Most, will want you to be available during the hours they're working, not just during the work hours for your time zone. That's a big issue in that they want it to be convenient for them.
With some companies who use remote developers, they will have them come at least once/month to their location for face to face team meetings. Proficiency in English is also very important to them as is communication in general. Having a good reputation on sites like this or the Developer Community is always very helpful.