This document summarizes a session on contributions of Web 2.0 technologies. It discusses tagging, social bookmarking sites like Delicious and LibraryThing, adding tag clouds to library catalogs, and topic maps. Specific topics covered include how tagging differs from controlled subject headings, how Delicious and LibraryThing allow saving and sharing bookmarks and book lists, using tag clouds to represent tags visually, and how topic maps standardize representing and sharing knowledge through topics, associations, and occurrences.