2013 promises to be another great year for observers of the Transient Sky! Right now, it looks like we will have not one, not two but possibly three naked eye comets [C/2011 L4 (Panstarrs), C/2012 F6 (Lemmon), C/2012 S1 (ISON)] including one that may turn out to be a Great Comet [C/2012 S1 (ISON)]. The Perseid Meteors of August will be observable under dark Moon-less skies. Also the small asteroid 2012 DA14 will fly past the Earth at an incredibly close distance of 21,000 miles or 1/10th the distance to the Moon on Feb 15.
Doug Snyder of the Huachuca Astronomy Club (HAC) has created a very handy single page summary of 2013. His 2013 sky calendar can be downloaded from the HAC site here.
Another useful list of 2013 sky events can be found at the Astro Guyz blog.