I have to respectfully disagree with Gordon. Particularly when you're approaching a 1:1 bittering to gravity ratio I think that a good base malt is exactly what you need when you are going to pound a beer with American variety hops. When Simcoe hops first became available to homebrewers, 2004 or 05 I believe, I brewed an IPA (OG 1.070 and 70 IBU's) that was 100% Fawcetts Optic malt and all Simcoe in order to get an idea of what the bittering, flavor, and aroma of Simcoe was like. Since then, I have brewed the same recipe two or three times a year in order to always have it on tap. It's one of my favorite beers. The Optic malt creates a great base to balance the bitterness of the hops. I've brewed this recipe a couple times with Rahr pale malt and don't like it as well as the Optic batches. Not saying you can't brew a great IPA with American base malt or that the hops shouldn't be the focus in an IPA, because they obviously are, but for my tastes I prefer to have the malt also be an attribute in the flavor profile. I've entered this recipe in half a dozen competitions, it has always scored high and never failed to place, so apparently the judges like it as well!
Interesting, too, that in one description of historic IPA's, (can't remember the source, probably Daniels), it states that their color should "reflect the color of the malt", or something along those lines. The suggestion was that early IPA's were typically 100% base malt. Similarly, I've taken a German Pilsner recipe, bumped the OG up to 75 and IBU's 75, 100% Budvar malt, 100% Crystal hops. Heaven in a glass! The aroma that floats around in that giant, white head of foam is amazing and again, the malt plays a significant role supporting the hop bitterness and flavor.