I'll begin this thread by sharing a fun kit that I recently assembled.
Otona no Kagaku (Science for Adults) is a series of "Mooks" (magazine/book) published by Gakken in Japan and available elsewhere through sources like Books Kinokuniya, Make Magazine, jlist.com, etc. I bought mine from Books Kinokuniya in San Francisco's Japantown for about $40.
Wish I could read Japanese better! Besides containing the assembly instructions, the magazine portion of the kit also includes general photo-enthusiast content, along with unrelated topics like the life cycle of swine flu in comic form.
Enough talk, let's get started!