Not sure if there's been a thread about sexy girls in terms of the NES here, but just in case there isn't, I'm going to start one. I can't think of all of them right now, but here's a few off the top of my head:

"Moby" from Chitei Senkouu Vazolder:
Struttin' around in a leotard battling monsters beneath the earth's surface. This chick is hot!

"Cherry Grace" from Golgo 13:
She'd probably be in my Top 5, because she is SO hot. She wears black (sexy color for women's clothes), has hot legs, an outfit that shows her sexy abs, long brown hair, the works. I bet Togo must've had a hot time doing the hump with her.

"Irene Lew" from Ninja Gaiden:
Well, she's never been in any revealing clothes or anything, but I've liked Irene for years, and her and Ryu Hayabusa were one of the first anime/game couples I ever got obsessed with, followed by Iris and Zero (Megaman X4), and then in 2000, Heero and Relena from Gundam Wing made the addiction spread. Why isn't there shitloads of Irene and Ryu fanart on places like deviantART and stuff? Also, I think Irene's got potential to be "hot".

"Jennifer" from Chou Wakusei Senki Metafight
She created Kane Gardner's battle tank, The Metafighter (or so a person from YouTube tells me), and I believe she's also Kane Gardner's love interest (Would kill to see romantic pics of them!). I've never seen her in a sexy or revealing outfit or anything either (In fact, I haven't seen any pics of her other than the "Metafight" box cover or the art gallery in Sunsoft Memorial Vol. 4 for the PSOne, or this fan-made flash I'll get to in a minute), but she's another one that might have potential to be hot. You can see a good fanservice shot of her in one shot of this fan-made flash video:

http://www.youtube.com/watch?v=6akuaH9cHEc

But it's in japanese with no subtitles.  I wonder if Kane and Jennifer kiss in the ending of Metafight....

"Leila" from Rolling Thunder:
The pretty damsel in distress that our hero, The Albatross must rescue. She's even hotter in the second game.