I use a product called Powdered Brewers Wash in the kitchen constantly. It is meant for soaking and dissolving organic materials in brewing that are in places that are very difficult to reach. It also works for baked on, burnt on, tea stains and pretty much every other tuff deposit; sometimes it take sitting a day or two. It has one good reason to read the fine print (guess who didn't) it will DESTROY Teflon coatings.
Woolite diluted 20:1 with water is the perfect item for cleaning automotive carpets.
Probably well known, but salt attracts moisture and is great for cleaning spills that stain (red wine for example) simply dump a heap on the still after you have patted it dry.
If in doubt vinegar will clean it, honestly it is our primary cleaner.
A ball of aluminum foil is your best friend for quickly cleaning steel. It is softer than steel and will not scratch, but harder than rust or deposits; I've used this to clean machines, counters, sinks, cookware, knives, tools and the list goes on and on.
A razor blade with the corners ground/filed/or otherwise rounded is your best friend. The rounded corners greatly reduce the risk of gouging and it is a great scraper for glass top stove or counter tops.