Run these in your developer console on the Steam website to easily scrape and consolidate information about your Steam account.
badges.js - Use on the badges page to see how much it would cost to buy the remaining cards for sets that are almost finished.
gems.js - Use on your inventory page to see which card sets are worth the most gems.
market.js - Use on any marketplace page to remove old listings that are higher than the current lowest price.
prices.js - Use on your inventory page to see which of your cards have sold for 10 cents or more on the marketplace.
search.js - Use on any page to open tabs for all new (non-free, non-VR) games in the past day (currently buggy).
wishlist.js - Use on your wishlist page to automatically remove any games that are no longer for sale or have a "very negative" rating.