This week's favourite brick is the 2x2 Turntable Base, which has been used since 1977 in 783 sets (to date).
Now this piece, when combined with the 2x2 Turntable Top is great for angling parts attached to it. A very common use on both official sets and MOCs are turrets or weapons, as the turntable is able to rotate 360 degrees. It is also small enough to fit in most places, making it more practical than its big brother, the 4x4 turntable.
As well as this, another use that not widely known, is the texture it can create. Like many pieces, when used just by themselves, an interesting texture is created, and when multiple pieces are used together, the result can be an attractive design. As seen in the MOC pictured, it is used as a border, but it can be used in a variety of ways; anywhere you want to have a unique texture that also shows the colour beneath it.
The piece on Bricklink: https://www.bricklink.com/v2/catalog/catalogitem.page?id=666#T=S&O={"iconly":0}
The featured MOC on Flickr: https://www.flickr.com/photos/45244184@N04/8660280889/in/photolist-fgDuYH-eY9vnV-riiyP6-ecnSXW-r8x3Ks-echcMK-echc68