In one line, I consider myselves as a Hindu subscribing to the Lokayata or the Charvaka philosophy. Broadly, Hinduism school can be categorized into Vedanta, Sankhya and Lokayata. The Vedanta school is theistic, the Lokayata school is materialistic and rationalistic and the Sankhya school is somewhere in between these two schools of thought.
The Lokayata school tries to explain the universe without introducing the (useless ?) notions of God or Devil. Lokayata roughly means one who believes in the physical reality of this world and nothing else (Loka means world). In this school, "truth" is that which can only be perceived by our sensory organs, i.e., eyes, ears, nose, tongue and nerve endings responsible for touch. With modern day technological innovations, we might as well add instruments used by humans everyday like multimeters, radio receivers, oscilloscope, miscroscope etc to the above list of human sensory organs. Personally, I consider it a triumph of this school of thought in that it comes so close to human scientific spirit.
The principle exponent of Lokayata philosophy is considered to be Charvaka probably around 600 BCE and the philosophy appears to have "died out" around 1300 CE. There are some who claim that Carvaka was killed by Yudhisthira after the Mahabharata war for the "crime" of declaring that the Vedas are not the ultimate sources of knowledge.
Its sad that very few of the original works remain and much of what we know about this school is from (often biased and misunderstood) commentaries from Hindu and Buddhist opponents. You might find the following links useful to know more about this beautiful and one of the oldest schools of rationalism.
Taken from my webpage at http://www.cds.caltech.edu/~nair/aboutme.php