Predict and then create a histogram of the leading digits of the file sizes of the non-zero-length files on your computer.
[SPOILER: when I did this once I found sharp peaks around digits that weren't 1. You are likely to see this if you have a large number of files around a particular size, examples: a) whatever your digital camera typically produces; b) whatever size your software encodes a typical song into. These files violate the assumption that you are sampling sizes over a wide range of sizes. After excluding these files I observed Benford's law quite closely on the remainder.]
Interesting, but can't this be explained by the distribution of file sizes. There will generally be many small files but fewer and fewer larger files. So there will be more 1k files than 2k files, more 2ks than 3ks, more files between 10 to 19k than 20 to 29k, more files between 100 to 199k than 200 to 299k etc.