At the heart and soul of Web 2.0 is one magical “I” that I have always used in Chrono Tron - Innovation. Yet, if one particular idea becomes quite popular in the web, be it 2.0 or 1.0, the idea is ripped off and a million other people just replicate it for the sake of emulating the original success. (Think Milliondollarhomepage) In some cases, this is quite useful as the new sites have the enhanced features of the original service but most of the time, this is blatant ripping and just crowding of the world wide web. Web 2.0 has a lot of popular ideas - Social Bookmarking, Social Networking, Photo Sharing, Memes, etc. Here check out the list of services in the popular categories alone. While I will not call them all clones or replicas, basically they may have built on the idea of the first site to develop that concept, but when something is a plain-clone, I will point it out. If there is nothing different about a particular service, then you will find no comment next to it. This is in the order of my favorites as well as the overall bests.

Note::
1) My Favorites are double starred **
2) The links in my comments are the links to reviews at various sites.

Social Bookmarking::

• Del.icio.us - The site that started this revolution and #1 currently but getting a bit complacent.
• BlinkList - Tons of great features and AJAX embedded fully. **
• Diigo - A Socialbookmarking site which lets you do a lot more with the links
• Spurl
• Furl - Good features
• Simpy
• Ma.gnolia
• Shadows
• Kaboodle - Social Shopmarking
• ClipClip - Save a page or a part of it and others can comment about it.
• Indiamarks - Social Bookmarks for Indians
• Yahoo! My Web 2.0 - No idea why Yahoo! has this after del.icio.us.
• Blogmarks
• Netvouz
• KMFavorites
• RawSugar
• Unalog
• All my favorites
• IKeepBookmarks
• Ticklr - For lawyers
• Tagsy - Social Bookmarking and Feed management
• Rrove - For Places/Locations