A system, comprising: first and second federation servers (312A, 312B) each with a set of registered computing resource providers (314A, 314B, 314C), wherein a computing resource provider offers computing resources in different software and services consumption models including Infrastructure as a Service, Platform as a Service, and Software as a Service, wherein the computing resource provider offers information on which types of computing resources are allocated and which types are available to be allocated to registered users who issue on-demand computing requests; and wherein the first federation server communicates directly via a network with the second federation server such that the first federation server has a computer-readable federation catalog that lists computing service providers and their computing resource offers to satisfy the on-demand computing requests, wherein the federation catalog of the first federation server lists the second federation server, when registered, as a computing resource provider, and wherein the federation catalog of the second federation server, when registered, as a computing resource provider, lists the first federation server, when registered, as a computer resource provider, wherein the first federation server provides an interface that, on request, provides updated, computer-readable catalogs of computing resources and computing resource providers linked to the first federation server, wherein the second federation server maintains communication with the first federation server to: request an updated computer-readable catalog of computing resources and computing resource providers registered to the first federation server; or communicate a user's on-demand computing request to the first federation server; or list, provision, use, and manage resources for an on-demand computing request addressed by the first federation server and the computing resource providers registered with it. first and second federation servers (312A, 312B) each with a set of registered computing resource providers (314A, 314B, 314C), wherein a computing resource provider offers computing resources in different software and services consumption models including Infrastructure as a Service, Platform as a Service, and Software as a Service, wherein the computing resource provider offers information on which types of computing resources are allocated and which types are available to be allocated to registered users who issue on-demand computing requests; and wherein the first federation server communicates directly via a network with the second federation server such that the first federation server has a computer-readable federation catalog that lists computing service providers and their computing resource offers to satisfy the on-demand computing requests, wherein the federation catalog of the first federation server lists the second federation server, when registered, as a computing resource provider, and wherein the federation catalog of the second federation server, when registered, as a computing resource provider, lists the first federation server, when registered, as a computer resource provider, wherein the first federation server provides an interface that, on request, provides updated, computer-readable catalogs of computing resources and computing resource providers linked to the first federation server, wherein the second federation server maintains communication with the first federation server to: request an updated computer-readable catalog of computing resources and computing resource providers registered to the first federation server; or communicate a user's on-demand computing request to the first federation server; or list, provision, use, and manage resources for an on-demand computing request addressed by the first federation server and the computing resource providers registered with it. request an updated computer-readable catalog of computing resources and computing resource providers registered to the first federation server; or communicate a user's on-demand computing request to the first federation server; or list, provision, use, and manage resources for an on-demand computing request addressed by the first federation server and the computing resource providers registered with it.