veerasivakumar,
You might try OpenJDK. The openjdk-6-jre package on Debian has an installed size of 740kiB (i386:
http://packages.ubuntu.com/intrepid/openjdk-6-jre).
Note however that it has a lot of dependencies, and the actual size it takes up on you disk will increase for every dependency that you install.
A Google search also shows at least one company distributing IBM WEME (
http://www-01.ibm.com/software/wireless/weme/) as a lightweight JRE - but note that that's Java ME, which is a cut-down version of Java. If Java ME suits your needs, then Sun also provides implementations:
http://java.sun.com/javame/index.jsp