In October 2007, the Wall Street Journal mentioned Startup Schwag on the front page, below the fold. That yielded ~15 signups for the ~$20/mo service, though admittedly its appeal was a bit niche.
The traffic comes in huge waves. It jumps 500x in seconds and dies down almost as quickly. In my case there were aftershocks as the news piece was aired around the world.
I don't think it drove more than about 100 extra visitors - truly a drop in the ocean. As a kind of direct marketing I think it was pretty much useless as the readership is so broad whilst our business is so specialist (no use in exposure unless it's to the right audience).
But we can now mention the WSJ piece as a kind of credibility signal. And for that it is great.
It's hard for us to know how much residual traffic we still get from Better Homes & Gardens, since there's no referrer to track people coming from magazines.
The amount of traffic she got from these was minuscule in comparison to popular online sources (Design Sponge).
The magazines in particular do tend to get put online and feed a small amount of views over time.
I got ~500 uniques more that day. I guess in 2004 german TV audience wasn't too much into internet ;)
For top cable shows (top 5 in weekly cable ratings), a rule of thumb we've found works for planning is 100 thousand uniques per second of time the domain or URL is shown or spoken, during and following the ad. If the brand is the domain, that counts too.
So 15 seconds of clear call to action exposure can drive 1.5 million uniques. Numbers are lower without a call to action.
Even when I used to work for a major TV station and we did very strong promotion in and around well viewed prime time shows the spikes in traffic were nothing shocking.
Of course this says nothing about the long term effects.
And be careful with email mailings, especially during office hours. Apparently most people have nothing else to do but check their mail every minute and click on every link in it. Huge traffic spikes.
In this case it worked relatively well, because (probably) there is a segment of the public of the site that is more on TV than on internet, so they saw the mention on TV and then went to the PC
I doubt you can get this kind of result from a TV mention (or ad) of HN ;)