Is their any disaster recovery technique to make redundancy between blades?
Replace "Blade" with "Server" and you get the answer. Blades are independent servers. Standard technologies do not become invalid just because you pack them dense into a blade center.
Can it be possible- Memory and storage sharing between blades?
Yes, it is possible - shared memory between computers as single instance image exists. It is not feasible, though, and a nieche technology, mostly limited to special very rare Hypervisor-Scenarios. Generally "plan your servers as you need them" is the solution.
If you want to research such technology, start at http://en.wikipedia.org/wiki/Single_system_image - there is also a list of software as a starting point. Again - this normally makes little sense. Do not even start thinking unless you have a Infiniband QDR backplane.
Redundancy in virtualization- Which applications and technology can be used with redundancy?
The same as with any other server. Again, blades are not anything else than a different physical packaging of servers. Use the normal technologies that you know as a professional admin and just ignore that they come in a special form factor.
THe CHassis itself will rarely fail - I use a Dell 1000e myself ans seriously, all active components are redundant (6 power supplies, 2 chassis controllers, 9 Fans). What can fail is the KVM master module and the backplane. I dont care about the KVM (does not stop blades from working) and the backplane has no active elements.... so it is unlikely to just fail.