Only a handful of Game Boy games make use of the SNES features when played using a Super Game Boy. I started a Super Game Boy listing project a few years ago over at GSCentral.org and later moved it to http://luigiblood.0fees.net/board/index.php.

Here are some Youtube videos showing the super Game Boy features in great detail.

https://www.youtube.com/watch?v=ksHirSih4XU - Contra The Alien Wars
https://www.youtube.com/watch?v=9lk1b_aiKJE - Desert Strike
https://www.youtube.com/watch?v=nPV6SgAzYP4 - FIFA 97
https://www.youtube.com/watch?v=6Msg7u5QlJE - Madden 97
https://www.youtube.com/watch?v=FyRoXkpg-FQ - Pocahontas
https://www.youtube.com/watch?v=quGCbDkW4og - Donkey Kong 94
https://www.youtube.com/watch?v=a-i5cQNQz7Y - Animaniacs
https://www.youtube.com/watch?v=66KA11Q6DTM - Pokonyan
https://www.youtube.com/watch?v=Yr-hqPtUx4s - Nekketsu Beach Volleyball
https://www.youtube.com/watch?v=rR4OTnoTgB4 - Pro Mahjong Kiwame GB
https://www.youtube.com/watch?v=v-U5QclS1jQ - Toy Story
https://www.youtube.com/watch?v=Z4DSuUDYG1I - Small Soldiers
https://www.youtube.com/watch?v=aez80rxLMnA - Fatal Fury
https://www.youtube.com/watch?v=S0CY_C5Lrpo - Solar Striker (default Pallete)
https://www.youtube.com/watch?v=uTJkFNHrUD0 - Tetris 1.0

There are a few other games not covered yet, and all of them have something to show off The sadly yet seldom used Super Game Boy hardware capabilities.