While there might be very specific agencies that handle the research for you globally, the best thing for you is to first limit the list of countries, and more importantly cities / regions where you would like to move. There are quite a few things to consider, including:
- The language you have to use during your work and generally
- The country's visa laws (for South Africans)
- Citizenship laws
- If you want to bring a partner / childrens / family what laws apply to them
- What kind of jobs are available
- The salary range you can expect (and whether that salary range is enough to obtain the visa in the first place)
- Whether the locals are friendly when encountering expats, or not
- Wheter you would like the climate of the region
- And lots of other things. Generally you might want to go there as a tourist first to check it out whether you actually want or could live there, or not
Internet forums, and sites like this one would be a good start for this, but don't expect a comprehensive list, as they would all depend on your circumstances.
Once you managed to get the list down to a few candidates, you should contact some job sites and headhunters who operate in that region, send them your CV and ask them about advice. Depends on the region (especially on the shortage of the local/easily hireable developers) they might be interested or not.
Ultimately it will be up the the company you'll be working for to decide whether you are good enough to warrant the extra risk and costs in hiring you. Usually the more experience you have, the better your chances.
Just to give you some specific example: I'm usually involved in a few interviews in London, United Kingdom, and we do interview and hire people who don't yet have the right to work in the country (we do have South Africans working here as well for example), but mostly for mid, senior (and higher) level positions. For graduate and junior level there are usually enough local or EU based applicants, who are much easier to hire.
Additionall in the UK if you can get the work visa, then as a Commonwealth citizen you'll get some additional rights (for example voting on national elections, something that is usualy not allowed for expats without citizenships in most countries), that might be useful.
That said the best thing you could do is is to start looking around, and get more experience in a field where there are shortages in your chosen region.