From The Big Issue (much more at the link):
Scandinavian settlers also made a very positive contribution to the development of England, which is overlooked by contemporary chroniclers. From archaeology we know that they played a key role in the massive growth of urban life in the 9th and 10th centuries. In towns such as York, London and Chester they established major trading settlements, importing exotic goods including wines and silks.
The Vikings, or the craftsmen they brought with them from the continent, developed mass production of affordable pottery and jewellery; indeed they provided a catalyst if not the engine for what has been described as the first Industrial Revolution.
In the countryside they contributed to the break-up of the massive estates held by royal and ecclesiastical landowners and accelerated the market in the buying and selling of land, leading to a great privatisation in land ownership. In places like York they appear to have opened up access to rural products, previously limited by the system of tribute, improving access to a wide range of foodstuffs.
They also left their mark on the countryside in the naming of hundreds of villages, such as those ending in the suffix –by, the Danish word for village, which also gives us the term by-law. The Anglo-Saxons also adopted Scandinavian personal names, so that by the last quarter of the 11th century, half the names in Nottinghamshire and Cheshire were of a Scandinavian type. They also gave us many everyday words which entered English, such as happy, husband, window and plough.
In summary, like many immigrant groups, the Vikings did not have access to the media of the day, and consequently often suffered from a bad press. Due to the Victorian elevation of King Alfred of Wessex into a Boy’s Own comic book hero, we tend to see the Anglo-Saxons as the ancestral ‘us’ whilst the Vikings were the ‘others’, although the Anglo-Saxons were of course simply a previous generation of immigrants from North Germany and Denmark.