I found these wonderful examples of pattern mixing while glancing at a blog called Project Beltway. The entire post was great, but these two photos caught my eye in particular. I love how this chap is wearing a plaid tie with a plaid suit, and he throws in another check with the shirt. In my opinion, the ability to harmonize patterns is true sartorial talent. The monogram on the sleeve is nice as well.
This is another picture from the same post, and again, I like the mix. The knit tie is wonderful, but my favorite item is the pocket square. It matches nothing, but it seems to fit.
The entire post can be seen at www.projectbeltway.com/