Sparkfun Electronic's $100k giveaway hasn't helped traffic in the longterm

I don't think this is a relevant statistic. Sparkfun makes money by selling items, not page views. There might not even be much correlation between page views and sales: If only 1% of their page views are actually people buying things, you could have double the actual sales or half as many and only move total page views by <= 1%.

For some context:

The original announcement - http://www.sparkfun.com/commerce/news.php?id=305

The aftermath - http://www.sparkfun.com/commerce/news.php?id=322

I expected traffic after the promotion to be significantly larger, but there seems to be no effect. So the $100k really had no affect on the number of customers they have, and though it seemed brilliant at the time, may in fact be a failure.

The lesson: big publicity which doesn't last long probably won't get you anywhere.

On the contrary, zoom back so you can see November 25th when they announced giveaway day. Better yet, pull back to "max".

Would one not expect a lull afterward? It was announced far enough in advance that people could choose to get their upcoming stuff on giveaway day. Maybe some of the free-getters were new customers who might repeat, but the value was in the press on November 25th.

My intuition tells me that a great deal of the traffic from free day was from people who don't know anything at all about electronics and simply wanted free stuff.

Some of them may be in it for resale value, but I know more than a few people who would take something simply because it is free.