Icelandic Rúv broadcaster reports that a few volcanoes in Iceland are ready to start erupting at any time with little warning. The volcanoes on top of the list are the volcanoes Grímsvötn (Grímsfjall) and Hekla. According to this news they are expecting that a Grímsvötn are going to erupt sometimes in the coming winter. In this news they also say that there are 35 active (dormant) volcanoes that can erupt at any time in Iceland. But some volcanoes are more ready then others to start erupting.
The news can be found here in Icelandic (Windows Media Player required to view the video).
There are many volcanoes in Iceland that don’t enjoy the publicity and the fame like the most active volcanoes in Iceland. That list contains mountains like Hekla, Katla, Eyjafjallajökull, Grímsvötn (Grímsfjall) and so on.
Hamarinn or Lokahryggur (Loki-Fögrufjöll) as it sometimes called is a small volcano under the Vatnajökull glacier icecap. Over the history it has not made many known eruptions. The last eruptions was in the year 1910 according to Global Volcanism Program. But according to Global Volcanism Program there might have been a eruption in the year 2008 and before that in the year 2006. The full list of uncertain eruptions can be found here.
This volcano is inside Bárðarbunga fissure system. But is independent of Bárðarbunga volcano. Hamarinn volcano does not have any caldera according to studies.
Icelandic Met Office has a good map of this area, to my surprise. That map can be found here. This map shows well all the volcanoes that are not listed at Global Volcanism Program website as there own volcanoes, or they might not even be listed at all on there web page.