Yes, it's Valentine's Day, but even if you're lonely and forlorn without love, there's good news: A bunch of iOS developers have put their apps on sale! The great Quarrel Deluxe is available for only 99 cents. Don't pass this one up if you haven't grabbed it yet -- it's a really quality word game with a lot of polish and great design. Dungeon Defenders: Second Wave is on sale for just a buck as well. Return7 is having a sale on the App Store, with both Debt Minder and Bill Minder on sale for up to