When I saw this challenge I immediately thought of Zatch Bell!. It was the first anime that made me aware of anime/manga. I used to watch it faithfully.
Just a few days ago I found this anime on a list of "Most Overrated Anime" and I was super pissed.If I never watched this, I probably would have never become an otaku. I got turned on the anime/manga such as Death Note, D.Gray-Man, and Law of Ueki just because I watched this. I also discovered my favorite seiyuu Takahiro Sakurai who did the voice of Kiyomaro. (Recently finished AnoHana mainly due to him voicing Yukiatsu.) So yeah... Whatever arguments that it wasn't at least a decent, light-hearting, and entertaining anime are invalid...
I also starting re-playing the video games due to a video game day and relieving the memories. (I find the fighting format for Mamodo Fury somewhat infuriating, but I kinda wanna finish it since it has much more characters than Mamodo Battles and the one for GBA.)I really need to re-watch the anime or finish the manga.
I also started drawing because of this anime. (Whether that's a good thing or not.) I drew a fan art of one of the characters from the movie and someone thought my friend at the time drew it and I thought she was an awesome artist so I kept at it.
Also really liked Teen Titans, but I probably should finish some Summer Homework...