Two impressive eruptions going on right now:
Soufriere Hills erupting on February 11, 2010. Image courtesy of the Montserrat Volcano Observatory.
Soufriere Hills just keeps on raising the bar during its new eruptive period. The volcano on Montserrat in the West Indies produced a 15 km / ~45 000 foot ash plume as the summit dome partially collapsed again. It was one of the biggest volcanic events at Soufriere Hills in the last 15 years, with 10-15% of the dome collapsing. One of the regional airlines in the West Indies have had to cancel flights due to the ash that has mainly been heading to the northeast. Pyroclastic flows generated in the collapse have been heading down valleys on the volcano out over the sea. UPDATE 2/12/2010: Boris Behncke pointed out this video of the 2/11 eruption with commentary from the director of MVO Paul Cole.
And speaking of the sea, the NASA Earth Observatory has posted an image of the ongoing undersea eruption at Fukutoku-Okanoba off Japan. The image is remarkable in that it captures the underwater plume of the volcano spreading to the north and west of the vent, but there is very little evidence of any subaereal manifestation of the eruption. The MODIS image was taken (along with an EO-1 image) only a few days after the Japanese Coast Guard caught footage of the volcano in action.