Rather than deep-link to manuals directly, which I think is terribly unfair given the work these folks put into these sites, I will organize them out in logical groups and tell you what they have available where possible. If you know 6502 assembly language, then you will just need the User Manual to figure out how to use the KIM. If you don't, consider getting the Programming Manual but better still look at a book like Richard Mansfield's Machine Language for Beginners, which is very straightforward and inexpensive on the used market (published by COMPUTE! Books). Note the colour coding I'm using to make it easy for you. The other colours: cyan is for the Hardware Manual, grey is for The First Book of KIM and yellow is for the KIM Hints; black bold is for everything else of note.
Ruud is a very enthusiastic KIM-1 user and offers a complete hardware description, simple interfacing instructions, copies of the User Manual, Programming Manual, Hardware Manual and KIM Hints, and plans for building your own KIM-1. Manuals are in ASCII and Extended ASCII (IBM graphics) formats. A very good page for all skill levels.
This is an unbelievably complete document archive and includes excellent HTML versions (bandwidth heavy but highly recommended) of the User Manual, Programming Manual, Hardware Manual, The First Book of KIM (in progress), KIM-4 Manual, Rockwell TIM Manual, Microchess and TinyBASIC. In addition, he has GIF scans of the Rockwell R6500 Designer Course and Don Lancaster's A TVT for your KIM (including the TVT-6 and -6L). An excellent page for reference.
This site offers mirrored copies of Erik's documentation as well as some other exotic manuals. In addition to the User Manual, Hardware Manual, KIM Hints and The First Book of KIM. there is also the KIM-4 Manual, MTU K-1008 Visable Memory Manual, and MTU K-1012 PROM/IO Board Manual. These are in a variety of formats, from HTML to raw scans and even PDF. Several are available in multiple formats for just about any viewer. Be sure also to look at the main page.
Rich Cini has a large number of KIM-1 documents in his archive, including MOS data sheets, User Manual, Hardware Manual, KIM Hints and The First Book of KIM. He also has a large number of scans of KIM Notes, the forerunner of the much beloved COMPUTE! Magazine (to which yours truly contributed a few articles in the last few years of Gazette), and other resources for other 6502 single-board systems.
This site is a little difficult to navigate, but does have a nice gallery of KIM-1 boards, peripherals and complete systems. It offers text versions of User Manual, Hardware Manual and KIM Hints, plus a GIF Schematic, a product circular with the KIM-1 hardware line, and several interesting magazine articles. However, the site layout is a bit wonky to work in.
This site has a large array of interesting software for download, along with documentation and often source. It includes Microsoft BASIC, MicroADE (assembler/disassembler/editor), Microchess, Q-Chess, Moser ASSM/TED (another assembler), Tiny BASIC and the Focal language. Many of these programs will require some serious KIM horsepower (not even KIMplement has enough for some of them). These are raw binaries; in KIMplement, load them with the "B" option.
Tom Pittman is the author of this port of Tiny BASIC, available for a large number of microcomputers. Not only does he have the Tiny BASIC manual in HTML and text, but he also has ports of Tiny BASIC to other, more modern systems for you to play with at your leisure.
A source copy of KIMATH, MOS's high performance floating point math library, and a 6502 simulator for Windows loosely based on the KIM-1.
Peter Jennings' personal page, the author of Microchess. Multiple versions available, including ports to other systems. I myself have ported Microchess to the Commodore 64, which you can get from the Secret Weapons of Commodore.
I mentioned this on the front page, but I will put it here as well since Bob is still producing his 4K memory board and KIM I/O board, newly made, all by hand and available for purchase as kits or fully assembled. Please pay him a visit.
Inevitably, Bo has a KIM-1 in his collection, but he hasn't gotten a power supply for it yet! Get with it, Bo! What kind of collector are you anyway?! ;) Bo also has a copy of the KIM Hints, although he has it linked as the "KIM-1 FAQ."
Steve has some very nice pictures of an original MOS unit.