[This question appeared, exactly as shown, on the DML recently. There's one like it every week.]
For all your genus-specific dinosaur art needs, your first stop should be the Art Gallery section of H.P. Mike Keesey's excellent Dinosauricon web-site at
dinosauricon.com/artists/index.html
For Giganotosaurus in particular, you want dinosauricon.com/genera/giganotosaurus.html and for a photo (not a line-drawing) of the skull, there's dinosauricon.com/images/giganotosaurus-bs.html (And, BTW., I also recommend Brett Booth's beautiful G. scene at dinosauricon.com/images/giganotosaurus-bb.html)
When the Dinosauricon doesn't give you what you want, the next step is the Google search engine at
www.google.com
Start with its image-search facility: a search for "giganotosaurus skull" (note the quote marks) quickly comes up with a page of nice thumbnail images (including one of H.P. Tom Holtz at www.geol.umd.edu/~tholtz/tholtz.htm
If that doesn't help, then the next thing is to use Google's whole-web search. This will generally give you a lot more hits, but exploring them is more laborious since there are no thumbnail images. Still, the same "giganotosaurus skull" search led me quickly to http://www.cmnh.org/dinoarch/1997Jun/msg00597.html and the subsequent articles in the Dinosaur Mailing List's archives, in which Giganotosaurus skull restorations were discussed back in 1997 (without much in the way of of results, unfortunately.)
But it's easy to get from the Google results to pages like www.paleoclones.com/images/fossils/large/053.jpg - a resin cast of a reconstruction. There's much more. Go find it.
No, this isn't really a dinosaur question: it's a mini-HOWTO for finding pictures on the internet. But it is perhaps the single most Frequently Answered Question on the DML, so it certainly belongs here in the FAQ.