Like the title says. I'm looking something with some versatility that can speed up over time and maybe drop random beats. I'm looking for a browser or desktop app. There are lots of links online, most use flash so are no good for me. Others are too simple. What you got?

Give Metronome EXP from EXPMuse a try. The free version is capable, but the Pro version is only $12 and contains a ton of additional features. Pretty good, either way.
 
https://www.expmuse.com/metronome.php
 
32- or 64-bit. With Pro, they email a license file to you with the payment receipt. Unzip the distribution file into a temp folder, create an appropriate folder in c:\program files\ and copy the unzipped files, plus the license file if Pro, to that new folder. Create a shortcut to it, and you're good to go.