This Google Maps mashup shows the locations of 66,000 Hotels in 168 countries. It is possible to search for a hotel and make a reservation directly from the website.
To search for a hotel just enter your chosen destination and the dates you wish to travel. Alternatively you can use the Google Map to zoom in on a location and select a hotel from those displayed.
Cheaphotels.ie also use Bing Maps when you select the 'map' option from the returned list of hotels after you undertake a search.