Do I have to get my Indian Visa before I leave Australia or can I get it while I'm travelling in Asia.?

I am going to Malaysia this month and will be then travelling onward throughtout Asia, finishing in India - do I need to get my visa in Australia before I leave or is it possible to get one in either Malaysia or Thailand.

Generally speaking, its better to get it before you leave.
You should try calling the Indian embassy or consulate to ask them and find out for sure.

I agree, you need to get your Visa before you leave. Your length of stay will determine what kind of visa you need to have. Some visa types have very involved requirements, such as financial records and doctor's approval. You should check with the consulate and start working on that now so it won't interfer with your trip!

Ask the Embassy in your place. Different countries has different requirements.