Its pretty much like a time machine with only small difference that , you can check websites and surf as they were in PAST ! Its very funny how internet giants google and yahoo used to look ! very boring and nothing interesting with just few options and boring colour combination's , very obvious as no CSS was available those days !
This Wayback Machine is very helpful and useful for those people who are researching on a history and all that footprints right from source of a particular website. There are hell lot of pages u can browse more than 200+ billion web pages archiving of which began right from 1996.
Check first looks of Google | Yahoo | Apple | Rediff