Amazon.com：Software for large-scale e-commerce
Apple: OS X is written in a mix of language, but a few important parts are C++. The two most interesting are
AT&T:The largest US telecommunications provider.
o provisioning systems
o systems for rapid network recovery after failure
Autodesk: A large number of major number of application in the CAD domain
Ericsson:o server platform.
o TDMA-CDMA HLR
o GSM-TDMA-CDMA mobility gateway
Google: web search engine, etc。
HP: Here is a tiny fraction of HPs C++ apps:
o C, C++, Fortran90 compilers, and linker for the new HP IA64 platform (these add to more than 1 million lines of C++ code).
IBM: o OS/400.
o K42: a high performance, open source, general-purpose operating system kernel for cache-coherent multiprocessors.
Intel:o Vtune performace analysis software
o compilers and optimizers
o lots of chip design and manufacturing software
JPL (Jet Propulsion Lab, NASA): Mars rover autonomous driving system (incl. scene analysis and route planning). C++ on Mars! Also lots of supporting software "on the ground" (i.e. Earth).
Microsoft:o Windows XP
o Windows NT (NT4 and 2000)
o Windows 9x (95, 98, Me)
o Microsoft Office (Word, Excel, Access, PowerPoint, Outlook)
o Internet Explorer (including Outlook Express)
o Visual Studio
Mozilla: Firefox browser and Thunderbird mail client (open source)
MySQL: MySQL Server (about 250,000 lines of C++) and MySQL Cluster. Arguably the worlds most popular open source database
Nokia: o Mobile Communications radio-station/internet bridges: FlexiGGSN (Gateway GPRS Support Node) and FlexiSGSN (Server GPRS Support Node).
Sun: o The HotSpot Java Virtual Machine is written in C++
Symbian OS: rationale: "[...] using C++ for all system code, from the kernel upwards." This is one of the most widespread OSs for cellular phones
KDE from linux is written in C++.
telephone systems: I think it would be almost easier to list the systems which arent written in C++