Let's see...
It's not a d20 thing, of course, but I own the Buffy RPG. Love the series. Angel, too...
I'll give Warcraft a look when it hits Austria (my dealer supposedly gets it next Wednesday-Thursday) but I'm not too likely to buy it. I played WC2 and its expansion but haven't found a chance to play WC3 yet.
And I don't care too much about playing in the B5 universe, even though I used to like the series. (It got worse near the end, at least in my opinion.) So... No B5 RPG for me.
I played Diablo I for hours on end - but I'm not too much interested in a Diablo RPG adaptation. Truth be told, D&D alone suffices for anything of that sort I might want to try; so I really don't need it.
I liked Starcraft but its Alternity conversion wasn't too good IMO. I might do Starcraft in HERO or BESM one day, though.
I haven't touched a superhero comic in ages (nor watched a superhero movie, though I do watch superhero comic tv series sometimes) but I picked up the new Marvel RPG. (Note: This one's not d20, either, of course.) It's way cool, BTW.
So... My interest in such adaptations really depends. Mostly, though, I'm more likely to just build it myself if it interests me enough to play it. (Buffy's an exception but the RPG just rocks that much.)