Contrary to a lot of standup comics and other social critics, I don't mind when people offer mindless chatter about the weather. It's one of those things that we all have a commone frame of refference for. It's way better than "Did you see last night's episode of Bridalplasty?"
You might say, "Well why do they have to say ANYTHING? Why can't we just keep our chit-chat to ourselves if we have nothing important to say?"
Well, that might be our functional operation of the future, but currently we're all still evolutionarily wired to make sure that other people are from the same tribe as us. 5000 years ago, sharing of common information was assurance that a stranger wasn't going to throw a spear through the back of your mouth and steal your stockpile of animal flesh. Now (in many portions of the country) we no longer have that actual threat, however your neurons still settle down when you make sure your cab-driver knows who won the NFC Championship.
Keep an eye on "How have you been?". This isn't exactly small-talk, because it's used for people we know who we haven't seen in a while. You may not realize it, but it's way different than "How are you?". "How are you?" is technically small-talk, because it is asking about the momentary status of someone's day, and it assumes the knowledge that the over-all scheme of their life is proceeding consistently. Asking, "How have you been?" is taking an awful gamble that they have been well, because you're basically asking if the last 8 months of their life have been remotely manageable. If the answer is "good", it doesn't really gain you much social currency. If the answer is "bad", then you're fucked. Because now you have compelled your barber to spend your entire haircut explaining the progression of necrotizing fasciitis--a condition you're almost certainly unable to aide in, as well as probably unable to have benefited from hearing about.
On the other hand, "How are you?" is asking, "Regardless of the over-all status of your life, how has your past 24-48 hours been going?" If the answer is good, you gain roughly the same social currency, but if the answer is "bad", you are way more likely to help improve their situation. This is because, if astronomically bad things have happened to them, you probably wouldn't be running into them at Radio Shack. The kind of bad things you hear about with "How are you?" are usually more commonly afflicting maladies such as "I have a headache" or "My DVR failed to record Jerseylicious"--the type of issues where solutions are more often floating around at the pedestrian level, and you may actually lend some productivity as a result.
And that's important, because people like small talk, and it's generous to offer forth that which people like. Small talk is how I got Justin Beiber to take a photo with me in my living room!