The devices you mention are FLASH based. They have page/sector erase, which Mahesh said he does not want. They also have SPI interface, not IIC.

Mahesh:
As far as I know, all serial EEPROMs are byte-for-byte reprogrammable, so they can be used in the way you want. Their main problem is the fact that they are very slow in writing, compared to RAM.
Check out the FRAM devices from Ramtron
These are serial, non-volatile devices with the same access speed as RAM.

Best regards,
Rob.