I have 3 printers. All show, in the utility a way to check the ink level, bu none came with the ability to do it.

Is there an aftermarket product/software to utilize these functions?

Canon BJC-2100
HP Deskjet 812C
Epson Photo Stylus 820

Thanks in advance

That depends on what operating system your using them under. Most companies like Canon, HP, & Epson offered this software with their printers that had those capabilites, eg: Epson used a software called Status Monitor. Lexmark has it with some of their printers as well, along with HP. However, printers designed to operate in older Windows os's like 9x do not have this capability in the newer Windows os's like 2000 and XP. Most of the printer companies (there are a few exceptions) do not offer drivers at all for those newer os's..... they leave that task up to Microsoft and usually the drivers offered by Microsoft (and included with the Windows os) are basic printer drivers. No special features are included. In order to get the same features you had in the older Windows os's, you must buy a newer printer that offers these features with included software. Most are USB connected printers.