ZSNES is a
Free, multi-platform, Super Nintendo Emulator.
Here are couple of little tweaks I would like to share (last used with zsnes 1.51.)
Using Keyboard and JoypadsSometimes you might use the keyboard, other times a gamepad.
ZSNES offers a nice feature, (useful if you only play 1 to 2 player games, like I do)
Tick the box Use PL3/4 as PL1/2
So, if you set your keyboard for player 1, and gamepad for player 3. Both will be useable for player 1. The same applies to player 2, for the player 2 and player 4 settings.

This way, you can switch from gamepad to keyboard any time, with no need to reconfigure your settings.
Crackles and PopsIf you experience any sound issues.
gedit ~/.zsnes/zsnesl.cfgOn line 178, change "auto" to "sdl"
libAoDriver="sdl"
Close the file.
The other settings can be changed from the GUI under Config -> Sound.
48000HZ with High Quality low pass filtering (you'll notice if you have a sub-woofer.)
Wide screen Aspect RatioSo you have a wide screen, and do not want any distortion when full screen. As far as I know, zsnes doesn't offer full aspect ratio correction.
Enter a custom resolution
My monitor is 1920x1200
Take the vertical monitor resolution,
divide it by 448
Take that number and multiply it by 512
round down
1371 x 1200
Enter that (click the lower SET button) then choose CUSTOM OD F

At that point press SET (the top button.)
Now zsnes should be full screen. Click the FILTERS tab, untick Use 4:3 ratio.

Note the larger vertical black bars, the emulated game screen is now proportionate.
If you are a true purist, keep the final size you choose a multiple of 256 x 224.
If you have a 1920 x 1200 screen, 1280 x 1120 are the largest multiples it can accommodate.
Experiment! Choose something that meets your tastes!
Alt + Enter will switch from full screen to windowed mode.

Have fun!