The Boylan's lemon seltzer is one of the best flavored seltzers I have tried. It has a perfect balance of flavor and carbonation and is a great refreshing alternative when you don't want a sticky sweet soda.
Tried some at the QFC supermarket at U Village in Seattle... stuff was great! Half the reason I bought it was for the bottle, but the taste really surprised me. It's not a sharp mineral taste to it, sort of soft. Quite a difference from citrus-flavored west coast seltzers/mineral waters (Talking Rain, Calistoga, etc.)