Light blue on white.
Light and Smooth 2.0
Lookfar Solarized Light
A theme based on the app Shiori, which has an Alfred-style interface for searching your Pinboard bookmarks (and a solid interface for adding bookmarks). For those who use Shiori, you can drag the sides of the application to make it match whatever window size you use for Alfred. Helvetica is actually the most Shiori-like font but I've used Courier because I find it easier to read.
Supporting options: Uncheck Fade in Alfred window, Hide hat and prefs cog.