The most popular Malayalam version of the Valmiki Ramayan is the Adhyatma Ramayanam Kilippattu written by Thunchattu Ezhuthachan. It is especially read during Malayalam month of Karkidakam, which is also known as the Ramayana Masam. You can now download Malayalam Ramayana Text in PDF format for free. The PDF version is in verse format.
You can download here at Google Documents - Malayalam Ramayan
The PDF version is from the Mobile Malayalam Ramayan version of P Harikumar.
You will need pdf reader installed in your computer or laptop to read the Ramayanam.