Actually, I think (for me at least) this would run the risk of pissing me off.
When all that I get in return for open source software is goodwill/karma/recognition, then there's no quid-pro-quo going on, and valuation is explicitly in non-monetary terms.
As soon as you start sending physical goods around, you're making it look like you're assigning direct value to my labour. I suspect my reaction to a company t-shirt in the post would be either
"You think so little of my work that it's worth one lousy t-shirt?"
or worse
"Not only are you profiting off the sweat of my brow, you want to me to wear this tshirt & give you free advertising?"
I don't claim this is rational - but I suspect I'd react emotionally that way.
The relative value of a t-shirt (<$10) is completely negligible when compared to the 'normal' wage of most programmers.
It's obviously a personal reaction, and therefore almost completely subjective, but I feel like the t-shirt is not reimbursing you for your work, but another way to say 'thanks', akin to a thank-you email, but that much more personal/sincere.
My philosophy on giveaways of this sort (and we do it quite a bit) is that if I lived in the same town, I would buy that person a beer or take them to lunch. It's not as though I'm paying them an hourly wage of $.05...I'm just saying, "Hey, that was awesome. High five!"
Everybody likes having someone buy the next round, right?
I think part of my pissed-off-ness would be that to me, the t-shirt is much less personal/sincere. Company schwag is almost the prototypical insincere, impersonal gift.
Still, just think if you have code in the linux kernel, you could ask t-shirts from just about every company in the world including government agencies and non-profits. You'd have more than enough clothing to last a lifetime of never doing laundry :-)
I wrote an awesome enterprise open source software, and instead of cashing up on support contracts, all I get are the bottom of the barrel IT tech support guys asking for free help.
So if I use Linux in my corporation, I am supposed to mail around thousands of T-Shirts now? You know, maybe a Microsoft stack would come in cheaper in the long run.
Hey Colin, if you're at OSCON next week, come see us at booth 326. We've got a T-shirt with your name on it. OK, it doesn't literally have your name on it. It has "Webmin" on it. But it's really nice. Heck, we'll give you two in different colors, if you want.
I don't think I've ever seen "swag" used. Are you implying that "swag" means trade show stuff while "schwag" is drugs? I've always seen schwag as the term used for trade show stuff, and I was unaware of the drug connotation. Google and Wikipedia seem to agree that it is an acceptable spelling (and they also agree with you that it can mean drugs).
"Swag", on the other hand, doesn't seem to mean what you think it means.
When all that I get in return for open source software is goodwill/karma/recognition, then there's no quid-pro-quo going on, and valuation is explicitly in non-monetary terms.
As soon as you start sending physical goods around, you're making it look like you're assigning direct value to my labour. I suspect my reaction to a company t-shirt in the post would be either
"You think so little of my work that it's worth one lousy t-shirt?"
or worse
"Not only are you profiting off the sweat of my brow, you want to me to wear this tshirt & give you free advertising?"
I don't claim this is rational - but I suspect I'd react emotionally that way.