frommers.com The online version of the popular guidebooks provides everything from lunch-spot recommendations to numbers of taxi companies.
uschamber.com/chambers/directory Here you can find links to local chambers of commerce in every state. While each local site is different, many provide information on transportation, area attractions, and upcoming events.
citysearch.com Choose a city and get information about local attractions, such as botanical gardens and the opera.
artinfo.org Get information on well-known museums and smaller galleries, with exhibition dates and times. (To browse museums by state, try museumlink.com.)