The Comic Book and RPG industries both have days were they distribute a sample of their product free in order to attract new costumers. What if that approach was taken with Esperanto, and a "Free World Literature Day" was set aside to distribute free Esperanto books?

It wouldn't have to just be Esperanto. The event could also have books in Spanish, French, German, and perhaps a handful of other languages, to make it a true world literature day.

The books could have the foreign text on the left page, and the English translation on the right, with a short introduction to the grammar in front, and a simple dictionary and phrase book in the back. The last few pages could be devoted to advertising, to cover the costs of the books. (I would imagine most of the advertising to come from tourism and language learning services, since these books probably wouldn't be that in depth, and said companies would be able to reach costumers who might not have otherwise considered learning the language they offer, or taking a vacation to a certain country.)

This might be an effective manner to emphasize linguistic and cultural diversity for one day, and bring Esperanto to the public's attention.

Hmm, this would have to be organised by, or at least be approved by book companies. It doesn't make me very enthusiastic.

I'd say go for it, but I can only see it being massively successful if it's in a place that A. it can draw positive attention and B. if the publishers etc are willing to give books away - the biggest problem I can see is what kind of quality books are we talking? US comics are different - they don't need to be printed on high quality paper to appeal to the fan base and they don't need to be laboured much in order to be produced (it appears that a lot of new comics these days are digitally enhanced a fair bit, compared with the penning of a novel or the finer pen detail of a Korean/Japanese Manhwa).

And I'm assuming that you'd want decent reads to interest the public, not just 'La kato sidis sur la mato. Fin.'

Basically it looks tough to organise.

At least in the UK, there's already a world book day where they give out free book tokens.

I think the real challenge would be finding enough advertisers to cover the costs. I don't know how one would go about convincing them. For one thing, somebody would have to create an organization to do this and push it through. It can't just be a loose community effort, a big project like this would require persistence with publishers, advertisers, etc...