It's really easy to make your own flavoured oils, and they are a great time saver if you want the flavour without the hassle of chopping the herbs.
I tend to use them in situations where I want the flavour but don't want bits of chopped herbs or garlic in the finished product.
1 glass jar with a seal-able lid
A good cooking oil - Olive or Ricebran are my favourite
1 bulb of garlic separated into cloves and peeled, or a similar quantity of clean dry fresh herbs
Put nicks in the garlic, or bruise the herbs and place in the jar, fill with oil until the herbs/ garlic are well covered, and sit in a dark warmish place for about a week before you start using the oil, keep the jar topped up so the herbs don't sit above the level of the oil and it will last almost indefinitely.
Favourite mixtures of mine are classic garlic and rosemary, and an Italian blend of oregano, garlic and marjoram.
Softer herbs like parsley and basil won't keep so well unless refrigerated.