1. A computer-implemented method for performance monitoring of a computer resource in a computer system utilized by a user community, comprising: collecting a first set of performance metrics that characterize a state of a computer resource in a computer system utilized by a user community; receiving first external information related to the first set of performance metrics from a source other than the computer resource, wherein the first external information comprises one or both of contextual information and user-provided annotation information; designating the first set of performance metrics as representing a first performance incident; storing a first incident record for the first performance incident in a data repository comprising a plurality of stored incident records stored therein, wherein the first incident record comprises the first set of performance metrics and the first external information, and wherein each stored incident record in the plurality comprises a stored set of performance metrics that characterize a past state of the computer resource and represent a past performance incident, and stored external information related to the past performance incident; searching the data repository using both the first performance metrics and the first external information to identify stored incident records that are related to the first performance incident, wherein if a stored set of performance metrics is similar to the first set of performance metrics or the first external information, or if stored external information is similar to the first set of performance metrics or the first external information, then the stored incident record comprising the similar performance metrics or similar external information is identified as a related incident record; and if any of the plurality of stored incident records are identified as related to the first incident record, communicating an alert to at least one member of the user community.