I just wrote a Javascript voltage divider calculator that gives answers with real-world resistor values that you can actually buy (EIA E24 and/or E96):
https://github.com/slugrustle/voltage_dividerTo try it out, download the code from github (green "Clone or download" button). You only need the file voltage_divider.html; just open this in a browser.
In addition to plugging my project, I also want to know if anyone has seen something similar. I've only seen voltage divider calculators that do simple algebra and give you a resistor value that you can't actually buy.