49. A non-transitory computer-readable medium having stored thereon computer-executable instructions that, in response to execution by a computing system, cause the computing system to: receive multiple annotations from different authors for particular content in a digital work; store the annotations in association with the digital work; provide a list of abbreviated versions of the annotations to a user desiring to access one or more of the annotations, wherein the list presents the annotations in an order determined by reference to a criterion; receive an authorization credential from the user desiring to access one or more of the annotations; and if the authorization credential is valid, provide a full version of the one or more annotations of the digital work to the user in context with regard to the digital work.
49. A non-transitory computer-readable medium having stored thereon computer-executable instructions that, in response to execution by a computing system, cause the computing system to: receive multiple annotations from different authors for particular content in a digital work; store the annotations in association with the digital work; provide a list of abbreviated versions of the annotations to a user desiring to access one or more of the annotations, wherein the list presents the annotations in an order determined by reference to a criterion; receive an authorization credential from the user desiring to access one or more of the annotations; and if the authorization credential is valid, provide a full version of the one or more annotations of the digital work to the user in context with regard to the digital work. 51. The computer-readable medium of claim 49 , wherein the criterion is a price assigned to each of the annotations.