NESticle is a freeware NES emulator for DOS/Windows95. I really love it.
Runs fast in DOS mode on my Pentium 60 with 16 megs RAM. It's even nice and
smooth in the Windows 95 version, which requires DirectX 3.0.
Opens ROMs with the .NES extension only.
NESticle lets you save your game at any point. You are given 10 "saved
state" slots per ROM. Press F9 for an instant PCX screen shot, which is
automatically given a unique filename so your screen shots don't overwrite
each other. You can even have NESticle record a movie of your game that you
can watch again at anytime. These movies are not too rough on the ol' hard
drive at 7K/minute (!).
The sound is quite accurate. There is an option to log wave output to a WAV
file (16-bit, Mono, 22,050 Hz sample rate).
I didn't encounter any... although some ROMs aren't graphically perfect
(i.e. Mike Tyson's Punch Out!!). I would like to see future versions
support the NES Zapper, Power Pad, and Power Glove :)
Other cool features include Game Genie codes support (yay) and joystick
support. Modem play is supported, but still buggy. It works, but only if
both players own the same exact ROM with the same exact filename.