Well, the malted barley isn't going to do a whole lot for an extract batch, but if you were thinking about making a small step up to partial mashes, this sounds like a good excuse. Look up Deathbrewers easy stove-top partial mash thread, it really doesn't take much more than a $5 paint strainer bag and an extra hour or so to your brew day. (Make sure the grains are crushed, otherwise you'll have to swing by an LHBS to get them crushed for you).
If you wanted to do another extract/steeping batch, the amber extract would get you to about 1.045. For a stout you'll need some roasted barley (0.5-1lb), and maybe a little black patent if you really want to make it dark. The amber will already have some crystal in it, so I wouldn't worry about anything else. Get enough hops to get you around 35 IBUs and a nice clean yeast and you'll be good to go.
That would leave you with the leftover gold extract and barley malt. You could add the gold extract to the stout recipe if you wanted to kick it up towards a RIS, even mash a few pounds of grain if you wanted to give a higher grav beer a shot. Otherwise, you could mash 4-5lb of the barley and add the gold extract and that would give you around 1.045-1.05. Add whatever specialty grains you want for the style brew you're looking for and go from there!