Okay I will play.... how about dehydrated salt water (just add water)... so to do your water change, you just empty out the water you want to replace and then pour in the dehydrated salt water, which creates more salt water when it hits your tank water. Instant water change...

Or how about an automatic tank glass cleaner... kind of like a Roomba robot vacuum cleaner, this would attach to your tank glass and automatically activate and scrape clean your glass daily. The corners might be tricky...