One of my favorite books, Smalltalk 80: Bits of History, Words of Advice, long out of print (and bloody unlikely to be reprinted), is available online. Link.
While some of the obstacles to getting a system as rich and complex as Smalltalk running acceptably on (say) an 8 Mhz 68000 with a megabyte of RAM have been removed by the last 25 years or so of progress, there are still many things to learn from the early struggles for performance. While techniques for on-the-fly code generation, incremental garbage collection and introspection practically everwhere are not unique to Smalltalk, they do all come together in a nice, comprehensible package, and you can appreciate How Bad Things Were in 64K address spaces, and so on.
Oh yeah, and the cartoons are funny, too.