Mainly the same information as in this help. You can also download the latest simulator version from here.
HP-15C LE Owner's Handbook
The HP-15C Limited Edition Owner's Handbook as a PDF file.
HP-15C LE Advanced Functions Handbook
The HP-15C Limited Edition Advanced Functions Handbook as a PDF file.
HP-15C / Simulator / DM15L User Sites
Hardware replicas, running the original firmware, of many HP calculators. The DM15L and the DM-15CC communicate with the Simulator via USB!
An HP-15C Simulator power user site with many example programs.
Logan West's HP-15C YouTube playlist
The playlist has 14 short videos about basic and advanced features of the HP-15C.
An article on how to implement Master Mind on the HP-15C and the Simulator.
HP And Others Calculators
The most comprehensive collection of HP calculators on the Internet. With information about their history, technical details and more.
Eddie's Math and Calculator Blog
Edward Shore's blog regarding calculators and mathematics. He has a lot of nice programs for the HP-15C.
Valentin Albillo's HP Collection
A collection of HP calculator articles, programs, pictures, brochures and books. There's a lot to read on this page!
On the official HP calculator site, you will find all currently available calculator models.
As of 2019, one model of the 10C series is still in production: The HP-12C, the financial model. It has reached a production time of over 36 years!
HP-15C Simulator Resources
If you do not have already installed Tcl/Tk on your system or if you do not have version 8.5.12 or higher, you can download it there. You can download either the source code or pre-compiled binaries for common operating systems.
DejaVu Fonts The "DejaVu fonts" can be downloaded from the sourceforge page.