I'm not using deep linking, so all the pages/states appear as http://site.com
Is it still possible to implement back functionality in this case? It looks like flex has a browser history feature, but not sure if it would still work given that all the pages are at site.com
The other option is that I would save information in the main file itself so I can go to the last page and retrieve whatever data was on it.
Anyone can advise what's generally the best practice way to handle back functionality?
Unfortunately I don't know of any other way to implement browser history (ie, back/forward) without using deep linking (eg, example.com/#foo). This is how the Flex browser history components implement it.
However, one thing you could do, if you need to keep the URL static, is stick your Flex application in a frame. That way the outter frame would still show example.com while the inner frame is at, for example, example.com/#widget=42.
The best practice and generally the only way to do it is to use deep linking.
it's best because the users can add a section of your application to "Favorites" and that's an important feature to have IMHO.
Check out the Flex docs on Deep Linking and the Browser Manager.