Mostly i solve my own problems and than make them bit more generic and polish them so that they are useful to others as well. Some examples are

1. Taxes: I have automated interest calculation,reconcilation of my accounts in different banks, calculation of ltcg/stcg in stocks as per my tax slab etc. Now every year i generate automated report and than spend sometime in reviewing before submitting it to tax authorities.

2.Organizing personal collection of movies/music: Finding the duplicates, making sure there is one copy, extracting thumbnails, downloading subtitles,trailers from youtube and movie info from imdb/wikipedia etc.