TinyCore is useful for some things. It's the de facto method to flash new firmware onto an APU for example. Light, quick, does the job from USB in seconds. For desktop I'd be looking more toward Arch base + minimal packages however. If you really needed a micro-light distro to customise to a particular purpose/job, Apline is probably the 'best' new kid on the block. NAS? Embedded controller? Network switch (yes switch, not router)? Alpine has you covered. It's extremely fast, light and tiny too. Horses for courses and all that.