Any kind that can capture images.

ok lets be a bit more specific...i was wondering if anyone knew what EXACT model of camera was used in say fahrenheit 9/11,supersize me,my date with drew?

Don't they tell you in My Date With Drew? It's just some handheld they found at Circuit City with a 30 day trial  money back gaurantee.

Ferenheit I haven't seen, but I think Supersize me was just some handheld too.

If it's a low-budget documentary, just use whatever DV you could get your hands on for the lowest price. Low budget documentary is about the content, not what it looks like. Just find the cheepest thing possible is my advice. literally, anything that can capture images is fine.

and hey what about sound?is there anything

The Panasonic AG-DVX100 is very popular among low budget filmmakers because it offers a 720p picture and a 24fps setting to emulate the film look. The AG-HVX200 gets you up to 1080p if you want an Oscar quality picture but you pay another $2500 or so for this. A new DVX100 runs you around $3000. This camera has been transferred to film before, and what its shot has played at festivals to great appeal (so I hear; no examples).

As for sound, you'll ideally want something that is separate from your camera. Onboard sound on any camera tends to be under par for a film. Any shotgun mike with a windscreen and DAT recorder should service you just fine.

Just don't neglect your lighting. A low budget lighting alternative to buying expensive studio lights is something like home security flood lights. They tend to be very bright and cover a large area. If you get high wattage ones, the effect should rival regular studio lighting.