Fotolia is an application based on desktop Adobe Air, where you can search for photos, imagery, vectors, and video available for purchase.
The price depends on the size and quality of your interested material. It has two credits (€ 2.40) for small pictures and up to 50 credits (€ 60) for movies in HD.
The Fotolia database is pretty impressive and for example, if you search results for 'Silhouette' (the element that is very useful for graphic design) has included over 250,000 results
Fotolia Desktop is an attractive application for professional photographers and graphic designers, although less serious users can not afford to pay for this type of material.