16. A computer program product comprising a non-transitory computer useable medium including a computer readable program, wherein the computer readable program when executed on a computer causes the computer to: identify a set of users that share a common set of characteristics by determining an online status of each user in the set of users and determining that the set of users perform same or related activities within a bounded time period and a defined geographical area; dynamically create a shared communication space for the set of users; create shared space settings for a first user in the shared communication space, wherein the shared space settings define what communications to and from the shared communication space are permitted or prohibited for the first user, and control, on a per information item basis, what information items can be shared; send to the first user an invitation that invites the first user to join the shared communication space, the invitation including the shared space settings specifying on a per information item basis what can be shared by the first user; and in response to the first user joining the shared communication space based on the invitation: apply the shared space settings of the first user to the shared communication space; filter information items provided to the first user based on the shared space settings associated with the first user including identifying a set of receivers of an information item in the shared communication space, the set of receivers including the first user, and determining whether to send the information item to the first user based on determining whether a number of receivers in the set is larger than a particular size; output the filtered information items and instructions that cause display of a user interface including the filtered information items when the instructions are executed on a client device; and receive communications from other users of the set of users about the filtered information items in the shared communications space.
16. A computer program product comprising a non-transitory computer useable medium including a computer readable program, wherein the computer readable program when executed on a computer causes the computer to: identify a set of users that share a common set of characteristics by determining an online status of each user in the set of users and determining that the set of users perform same or related activities within a bounded time period and a defined geographical area; dynamically create a shared communication space for the set of users; create shared space settings for a first user in the shared communication space, wherein the shared space settings define what communications to and from the shared communication space are permitted or prohibited for the first user, and control, on a per information item basis, what information items can be shared; send to the first user an invitation that invites the first user to join the shared communication space, the invitation including the shared space settings specifying on a per information item basis what can be shared by the first user; and in response to the first user joining the shared communication space based on the invitation: apply the shared space settings of the first user to the shared communication space; filter information items provided to the first user based on the shared space settings associated with the first user including identifying a set of receivers of an information item in the shared communication space, the set of receivers including the first user, and determining whether to send the information item to the first user based on determining whether a number of receivers in the set is larger than a particular size; output the filtered information items and instructions that cause display of a user interface including the filtered information items when the instructions are executed on a client device; and receive communications from other users of the set of users about the filtered information items in the shared communications space. 17. The computer program product of claim 16 , wherein performing the same or related activities comprises at least one of messaging on similar topics, composing documents related to similar information, playing related games, shopping online for same or related items or services and browsing within a group of related sites.