The model is a double-limbed elven bow, but the question applies to anything that creates a large number of islands. I have unwrapped it, producing many islands on the UV map that look similar. I would like to be able to id the corresponding parts on the model. I can select an island (using L), but the whole model has to be selected to show up on the UV map, so there's no differentiation visible. The major purpose is to reposition certain islands so the wood grain texture goes a different direction. Is there a way to do this? Thanks!

Think I got it. Selecting individual or groups of faces makes them show up on the map side.

If you click on the button indicated in the attached picture you will toggle on the "Keep UV and edit mode mesh selection in sync" action. This will show, when in edit mode, all the faces of the mesh in the "UV Editor" window. If you use the "L" key in the left window (3D View) you will select all the faces in each separate mesh element, these faces will then be highlighted in the "UV Editor".

Volcanic, could you post a screenshot here, please? I'd love to see what you are working on. Some of the terminology is somewhat alien to me.

While Keppel's suggestion provides probably the most straightforward solution, you can also use H [hide] and Alt+H [unhide] in various combinations to narrow parts down or just simplify your view as well. If you "hide" something while the cursor is in the UV window, then it will deselect those polygons in the 3d view [Note: this only works if you don't sync selection between the views as Keppel suggested], if you use "hide" in the 3d view [or with sync selection active], then it will actually hide the geometry.

I really need to start "wrapping" my head around unwrapping. This is one area besides modelling I fail at miserably. I've concentrated so much on rendering nice pictures, that I've totally neglected the deeper aspect of creation. I've picked up some on modelling, but unwrapping is a dark forest to me.