Typographica (cool typography-related blog) has a posting about the benefits of owning/perusing The Manual of Linotype Typography.

Hear, hear. I agree. I've seen and perused in-depth a copy of this book, and it is astounding. In a design rut? Page through this guy to get inspired. Sure, some would say that the look is dated (the manual is from the 1920s/1930s) but there are good things going on in this book. Drop the over-thick page borders and dated colors, but look at the spacing, sizes, and font selection. And some of the sample text used is simply priceless.

The Typographica article has several links to sample pages.

If you want to get really classically inspired, you could also poke through Alan Bartram's Five hundred years of book design.