While the Ebola response mapping jobs are in pretty good shape there are other open tasks where there is plenty of unmapped territory.
With an OSM account you can see the full list at http://tasks.hotosm.org .
E.g. http://tasks.hotosm.org/job/468 is completely undone (albeit 3 squares are being worked on as I write this) and http://tasks.hotosm.org/job/467 has just 3 squares done (with 2 being worked on). Both of these two tasks are linked to US State Department's Humanitarian Information Unit's MapGive program, which BTW has nice video intros/tutorials to getting started with OSM (http://mapgive.state.gov).
With an OSM account you can see the full list at http://tasks.hotosm.org . E.g. http://tasks.hotosm.org/job/468 is completely undone (albeit 3 squares are being worked on as I write this) and http://tasks.hotosm.org/job/467 has just 3 squares done (with 2 being worked on). Both of these two tasks are linked to US State Department's Humanitarian Information Unit's MapGive program, which BTW has nice video intros/tutorials to getting started with OSM (http://mapgive.state.gov).
If you have any questions you can ask at HOT email list https://lists.openstreetmap.org/listinfo/hot, Twitter http://twitter.com/hotosm or FB page https://www.facebook.com/hotosm -- or IRC (OFTC #hot) http://wiki.osm.org/IRC