I don't know of any apps, but I do have some websites.
is probably the best aviation site in South Africa. It excellent flight planning and weather features. You can plan your whole flight on this website using charts that have been scanned into a Google Earth type of map. There is also a mobile version of the site as well as an application that you can use to track yourself.
is a website hosted by the ATC company in South Africa. You can use it to file your flight plans online and also to get a preflight briefing. You fill in where and when you want to go and it generates a list of Notams, AIC's etc that are applicable to you.
Morza Mock Exams - Free Online PPL Mock Exams
is another site where you can take mock exams of PPL subjects for free, with CPL level exams in the works.
Hope these help.