OK, we may not be able to come up with 100 - but let's see how many we can. I'd like to compile a big list of suggested Kickstarter rewards as a reference for those considering launching an RPG-related Kickstarter project. I'll then put it up on RPG Kickstarters.
Pre-release limited edition printing of product, useful for playtesting
Separate booklet of maps
The core book for which a supplement is being Kickstarted
Hand-bound version of book signed by creators
A vinyl mat - this suggestion comes from Dave at Blackwyrm; tactical battlemats are the obvious application but for Dwimmermount we're doing a tracker to record the party's progress through the mega-dungeon and how the situation changes in response
You describe a scene, character, etc. which will be illustrated and published in the final book (e.g. this or this)
You and one of the artists play a game together and then choose a scene from your adventures to be illustrated in the final book
You create one of the characters that will be published as a pre-gen in future modules
As above, plus one of the artists does a portrait of the character you created that's published in the final book
As above, plus you get the original piece of art
As above, plus Sandra Garrity scupts a miniature of your character and chooses an artist to paint it for you
As above, plus you get a selection of Dwarven Forge pieces customized to build the dungeon your mini will explore