Already existing search functions in MoinMoin
TitleSearch - Search pages by their title
FullSearch - Full text search
macro/SearchInPagesAndSort - Search in selected pages and sort the result, all with regular expressions
GoggleSearch - By its syntax, a google-like search-macro/action, has to be completed/improved. See also MoinMoinTodo/ExtendedSearch
Thomas Renard/AttSearchTool - Search in Attachments