St Germain Liqueur
It is an unusual liqueur in that it has a myriad of citrus flavours, aromas and undertones.
Usually served straight, but can be mixed with champagne and dry or sparkling white wine but mixes well with most spirits and club soda.
It can be successfully used with fruit desserts.
For a range of cocktails see About.com
For cooking ideas, check The Nibble also many cocktail ideas, including the Mojito Pariisen.