What methods are available to create a snapshot of an oracle database for testing purposes?
If with "export/import" you mean the "traditional" exp and imp commands, than I'd say there is a better solution: 

expdp and impdp are much faster and much more flexible when copying a snapshot of a database (or single schema).

If the database is not huge (i.e. Terabytes) then expdp and impdp is the easiest way to achieve this. They are easily scriptable and can be started using SQL also. So no commandline access to the servers is needed (provided the dump files are stored on a shared storage).