Spreadsheets with lots of columns and lines with pretty colors are fun but there's other simpler ways to keep track of your brewed beer.
I tag my kegs before putting them into the beer cooler. Each tag has the beer style, when I brewed it and when it was kegged. Granted I have six kegs in my cooler, three on tap, but if you have more inventory then a list might be needed.
Unless you're into heavy beer production I don't see much value in making it too complicated. I figure when a keg is about empty and I put the second keg on tap it's time to figure what to brew next. At the beginning of each year I write down a list of what I want to brew.