Basil - Pungent and slightly peppery (inspires hints of cloves in the nose). A super common ingredient of Mediterranean food. Be careful how you use it; any dish with Basil runs the risk of being typecast.
Bay Leaves - Adds 'age' and 'maturity' to any dish with its earthy and arboreal flavour. Always remove the leaves before serving (so do not cut them up), and give it plenty of time to infuse through the dish. Stews and soups are brought to life with this flavour. I think a lot of people claim not to like Bay from smelling the leaves, but love the resulting infusion. In leaf form, it's just too much (personally I love the smell).
Chervil - Aniseed with parsley overtones. Used often in French cuisine for lighter flavoured dishes with Chicken, Fish, Eggs.
Chives - I would describe Chives as tasting like the smell of onions on a spring breeze. Goes great with earthy potato, eggs. The purity and simplicity of the spears of chive make it ideal for use as a garnish to a number of dishes. Go careful though, chive can make too much of itself like basil and take over the flavours of a dish.
Coriander - American readers of my blog know this as Cilantro. Pungent citrus and lemon notes both hit the nose and tastebuds. Many many Asian, particularly Thai, dishes use Coriander in their sauces. Unusually both the leaves and the stem contribute flavour, so use the whole green part of the plant.
Dill - Scandinavian favourite with its strong aniseed flavour; and essential ingredient for many fish, potato and egg dishes.
Lemon Grass - Strong citrus/lemon taste and aroma from this woody/fibrous stem. Like Bay it tends to be removed from the dish before serving.
Marjoram - An underestimated herb in my opinion. It is a Mediterranean classic similar in flavour to oregano but with a bitterness that is quite seductive.
Mint - More than just toothpaste and chewing gum, when used correctly mint compounds well with base flavours. It does not play nicely with other herbs. Once you see mint in your mixing bowl, do not add any other herbs (it just goes weird!). Potatoes, Lamb, Chocolate, Tomatoes all play nice with Mint. Sometimes you might be able to get your hands on wild mint; when you do it will be strong and super intense, boil with water to create an incredible mint tea.
Oregano - Peppery and rounded oregano was born to blend with tomato.
Parsley - Similar to Bay in my mind that some people think they do not like it; when tasted alone it can be a bit too strong. But when blended correctly with other herbs is forms a great base to build other flavours on. Grassy and salty somehow at the same time (uniquely savoury). The Flat Leaf variety has a much stronger flavour than the curly type.
Rosemary - Pungent and resin-like, to inhale this scent is to dive head first into a forrest. Goes particularly well with Lamb. Fresh varieties will release a sticky oil that tastes incredible when added to dishes.
Sage - Camphor and balmy goes very well with poulty and pork. Sage has natural antiseptic properties too which means a sage tea will help a sore throat.
Tarragon - Aniseed and dry grass/hay this herb adds dimension to other flavours. Goes very well with creamier sauces, leeks, soups and egg based dishes. To my mind it has an aristocratic feel about the taste. Never buy Russian Tarragon (it has no flavour).
Thymne - Lemon and mint combined with the down to earth woodiness of Rosemary. Holds it own very well against other strong herbs so can survive the long cooking of stews and stocks. Preparation can be tricksy, this is one that I do buy dried and pre-processed.