Using the facilities provided by SkyCat, GAIA is capable of downloading images from several surveys and catalogues from a wide range of sources, so for instance if your image has a world coordinate system associated with it, you can query the ESO catalogue of HST guide stars about any located within the bounds of your image. These will then be listed and plotted over your image. Similarly you can query the NED (NASA/IPAC Extragalactic Database) and SIMBAD databases and see lists of all the objects that they know about on your image. You can also display an image returned directly from the Digital Sky Survey(and then perform queries in other catalogues about this field). Named objects from certain catalogues can have their full information displayed in a web browser and may even have bibliography links to the ADS abstract service. Finally the HST archives are also available. Using these you can see what observations have been made of any objects on your image (and preview any generally available).
More recently GAIA has been extended to offer similar features, catalogue and image access, using the developing Virtual Observatory. These like the features above are found in the Data-Servers menu of the main window.
Note: you should take time to find what your obligations, in terms of the correct acknowledgement of copyright, use of service etc. are, whenever you use facilities such as those mentioned above.
GAIA -- Graphical Astronomy and Image Analysis Tool