Out of the 988 featured pictures on Wikimedia Commons in 2012, the five below were voted the best of the best. I haven't perused all 988 photos, but the 5 below are certainly worthy:
2. A long filament of solar material erupted out of the Sun's atmosphere
3. High-speed photography of a light bulb shot with an airsoft pistol.
4. A wide evening view to Måbødalen in Eidfjord municipality, Norway.
5. Yak near Yamdrok Lake, Tibet
Be sure to check out all the award winners at the Picture of the Year 2012 page at Wikimedia Commons.