I made Plain Email [0] just because I couldn't find any email client with clean work flow without distractions. I use it pretty much every day. Thinking about open sourcing it - just can't find the time to refractor it nicely.
I also built news aggregator 10HN [1] with throttling (ten best articles every morning and every evening). I use it daily and it helped to fight my procrastination a lot. It's also interesting to watch the data how stories evolve and get popularity.