Directly: my employer, who distributes software for analyzing the performance of computer systems. However, I don't actually do much software development any longer, and spend most of my time either teaching clients how to use it or actually doing the analysis for them.
Indirectly: my clients, which include banks, insurance companies, brokerage firms, and airlines.
We make it a point to remain independent of vendors, because we don't want a conflict of interest with respect to hardware vendors. We do recommend some software (in addition to ours), but that's for performance analysis, not applications.
With respect to mainstream processor architectures and operating systems, we are neutral -- we support all of them. We do learn a lot about what works and what doesn't work in these environments (because our clients tell us), but we don't make those kind of recommendations.
The most specific recommendation I have made is to "add a device to your network that performs this function. We predict it will have this effect." However, I didn't recommend a vendor (there are several, or they could build their own with a Linux or BSD system). As it turned out, they were already considering it and wanted to see if we came up with the same conclusion on our own.
Your turn.