Oh yeah. It's Squirrel Girl. She was only in one issue of Iron Man, but she has a bit of a cult following, especially on the Net. From The Unofficial Handbook of the Marvel Universe:

First Appearance: Marvel Super-Heroes III#8 (Winter, 1991)

Powers: Squirrel Girl is a mutant with several traits that are similar to or usually associated with squirrels. For one, she is extremely agile. She can also leap several stories. She possesses claws which allow her better grip for climbing. Her teeth and jaws are strong enough to rend wood. From the back of each hand, she can produce a retractable “knuckle spike” that has the same damaging capabilities as her teeth, and they are more combat-ready than her fingernails. Communicating with squirrels is another ability of Squirrel Girl’s. Squirrels she talks with will aid her, even attacking enemies’ en mass. Finally, she has a furry tail, a little over a yard (3 feet) long. Functionally, it was used to blind Iron Man in mid-flight as she held onto him. Further, she wears a belt with several large pockets attached to it, but they only carry a variety of nuts for herself, squirrels, and whoever may want any when offered.

Physical Description: Squirrel girl is a teenage-girl with claws and a three foot tail. On top of that, she has terrible eyeshadow. She grins a lot, apparently she's happy despite her uh, unusual lot in life.

History: (Marvel Super-Heroes III#8) - In the woodlands near Stark Enterprises, Squirrel Girl encountered Dr. Doom while on the way to meet Iron Man. Squirrel Girl jumped on a low flying Iron Man while he was testing an experimental radar system. After they both crash-landed, Squirrel Girl introduced herself and her abilities to Iron Man in order to win him over as a super-heroic partner. Unfortunately, Iron Man was not impressed, but before he could leave Dr. Doom disabled his armor and knocked him unconscious with a pulse-interruption ray. A tractor beam then hoisted all three of them into Doom’s flying craft.

Squirrel girl and Iron Man were both imprisoned within the same deathtrap; Iron Man was secured by energy draining bonds, but Squirrel Girl was unfettered within their prison. Spotting a vent, Squirrel Girl was able to open it and call for her squirrel friends. The squirrels jumped aboard the ship from the treetops, chewed through wiring, disabling Iron Man’s bonds, and attacked Dr. Doom. While he was being gnawed on, Iron Man and Squirrel Girl encountered Doom. Rather than meet defeat by squirrels, Doom opened an escape hatch, disappearing into a nearby river. Iron Man gave chase while Squirrel Girl waited shore-side but Doom escaped.