I was wondering if there was any way in the wizarding world that people separated by long distances could exchange messages or talk to each other INSTANTLY. I know they generally used owls but it usually took some time for owls to deliver the letters. They could appparate but that presents some problems like not knowing EXACTLY where the other person is at that time, or if you were underage. Why didn't the wizards use telephones?
Most would use the Floo Network.
I think it is a very reasonable suggestion that every wizarding home would have a fireplace (they'd use them for more than us, they are fairly common anyway, Fred and George are surprised that the Dursley's is blocked up). Floo Powder is inexpensive (two Sickles a scoop according to Pottermore) and we see the Weasleys teach Harry to use it at the age of twelve. (Yes, it goes wrong, but not I think because it is advanced magic). We also see that public spaces like the Ministry of Magic contain several fireplaces, and I'd be willing to argue that Diagon Alley shops, The Leaky Cauldon, etc have them. In JKR's writing on Floo Powder on Pottermore, she also makes the bold claim that every wizarding house has a stock of it.
Also: The coins used by Dumbledore's Army using the Protean Charm are an example of how there may be alternative ways to send simple messages without the need for a fireplace.
Finally, I'm afraid I don't think the Patronus is a logical answer for most wizards. I believe Dumbledore invented this (the HP Lexicon certainly says JKR said so) and I know that many wizards are incapable of producing one. Snape, for example, was the only Death Eater capable of it.
It depends on your definition of "long distance", but using a Patronus is an option. They've been shown to be capable of sending verbal messages a number of times in the later books, such as Kingsley Shacklebolt alerting attendees at Bill and Fleur's wedding that the Ministry of Magic had fallen, and can even be sent to multiple people/locations at once.
Another option is enchanted items such as the mirror that Sirius gives Harry in Order of the Phoenix, which enables two-way face-to-face communication (much like video calling does today) between whoever is holding each of the mirrors.
The exact range of these methods is unknown, as far as I know. It's unlikely that a wizard in England would be able to send a Patronus to a witch in North America (though we can't rule it out). The other consideration is the difficulty of conjuring a corporeal Patronus - although it's considerably easier to do in the comfort of your home or office than it is when in front of Dementors - which would mean it's only an option for more skilled, fully qualified witches and wizards.