A few days ago Yves-Alexis Perez asked me how many hardware sponsorship request I usually get from Debian Developers, that is how many people ask me to use Debian money to buy material that can improve their work on Debian — and indirectly Debian itself.
The answer is "too few".
Making it easier for our developers to improve Debian is a worthwhile investment of money donated to Debian.
Of course such a use of money should be motivated (i.e. you should be able to justify how the material you're asking for would improve Debian and why it should be Debian paying for it) and transparent (i.e. you should periodically report about what you're doing with material that Debian has bought for you to use).
The above two principles are what I've tried to convey in a new section of the sponsoring guidelines wiki page I've been maintaining for a while. Comments and improvements highly welcome!
Equally welcome are advocacy messages for hardware sponsoring to other fellow Developers, as suggested by Corsac.