Hi Girish,
If you are looking for some browser based free games, then there are lots of sites that you can check
These are bgames.com
Addicting games
And you can also check facebook.com for some fun flash games.
Yes Facebook has a huge range of games to play, Also you can get 60 minute trial download games from a heap of sites like wildtangent and bigfish games, Just google free download games and things like that should show up.