QUOTE (Bier Meister @ 10/14/09 3:01pm)

salsas are often (though not always) blended, while the pico is left chopped.
IMO, Pico de Gallo is a specific variety of salsa, that being diced tomatoes, onion, jalapeno (or serranon), cilantro, lime, and salt. There could be some very minor variations but that's pretty much it.
Pico de Gallo is a salsa but salsa can mean any number of sauces, be they cooked, raw, blended, chopped, what-have-you.
So Bier's answer, while technically correct doesn't exactly explain the deal.
In terms of a recipe, it's pretty much right there. Just dice those ingredients up. I prefer white onions to yellow ones because they're sweeter and better raw. Roma tomatoes are nice to use because they're plenty meaty. I actually also prefer it when they're not super ripe. The acidity is higher and the salsa doesn't get as mushy.
After you mix the salt in, all the ingredients will give off a bunch of liquid. Strain this off and drink it alongside tequilla but strain it off regardless so your salsa isn't all watery.
Lastly, the reason why salsa doesn't taste so great the next day is the onions. In case you're wondering. So just make as much as you're going to need.