Here's an example.
If you're running MySQL on Windows then you can use Address Windowing Extensions (AWE) which is supported by MSQL. AWE increases the maximum size of a user process from 2GB to 3GB which is what I have indicated in Table 5 of this article. It would give a 50% increase in addressable RAM for MySQL but you will find that it should give a greater increase in the memory available to your MySQL application. Running MySQL on Windows with 4 GB of RAM explains this in more detail.
Just remember it does not work on all editions of 32-bit Windows, it prevents MySQL using Windows pagefile, and you have to recompile MySQL.