Can anyone suggest some good search engines, websites or appstores to download free apps or softwares and get news about any apps and software?

Any good social sites where we can make friends like Facebook, twitter, and littlemonsters.com?

Can you suggest me some blogs and sites where I can make groups and communities or pages where we can share ideas?

Please suggest differnt websites where i can share videos eg. youtube, vimeo, photos eg flicker, pinterst, audio eg soundcloud.

Please suggest me some more such sites.

You already have some good starting places and they can lead to even more sites as you gain usage from them. Or just Google for more.