No, there's not.
There are some standard settings. In Microsoft Windows, you can use Device Manager to check the properties of a device. The "Details" tab has several properties for network controllers. You can also see many of these settings using WMI, with the WMIC command that is built into modern versions of Microsoft Windows (including Windows XP... and offhand I believe it may have been downloadable for earlier versions like Windows 98). e.g.:WMIC NICCONFIG GET /FORMAT:LIST
However, those will show some settings. Your question was, "Is there a utility that can easily show all configurable settings" (emphasis added by myself), and are interested in an approach which is not specific to the manufacturer. The answer is no. The reason is that manufacturers have been known to add additional controls, and have been known to do so in manufacturer-specific ways. Therefore, the only easy way to interact with such settings would be to use software made by the device's manufacturer.
That said, unless you're dealing with serious high traffic (more substantial than a business with dozens of computers... more like what "data center" of an Internet Service Provider), you probably won't benefit a whole lot from doing a lot of tweaking of minor settings. The key exceptions are wireless authentication, and perhaps wireless strength and MTUs.
When Wi-Fi first started to become popular, many cards had some settings that could be used to adjust wireless strength. However, I recently noticed that a standard command line software, bundled with an operating system, removed support for some of those settings because most drivers were now ignoring the settings anyway. (Therefore, confusion was the most likely result of having a setting that was not causing the document effect.) If you're seeking to maximize wireless strength, you would be much better off by using newer hardware that supports 802.11ac, rather than trying to adjust some setting from the 802.11g equipment.
Yes, you could probably get some improvement if you mastered some settings. For most people, such mastery is probably not going to be more worthwhile than just upgrading to more capable equipment that uses newer technology.