From the Arizona Politics blog:
The nine Justices finish deciding cases from the October term by the end of June (or, occasionally, the beginning of July), and some of the most difficult and significant cases end up being the last ones left. This year, the Arizona Legislature v. Arizona Independent Redistricting Commission still remains, along with the ACA ("Obamacare") subsidies, same sex marriage, and four other cases.
SCOTUSblog expects opinions on Thursday and Friday mornings. They run a live blog from the Court those mornings starting at 9:00 AM eastern time.
UPDATE: AZBlueMeanie says SCOTUS added Monday to the days for announcing opinions on remaining cases.
Pending cases (from SCOTUSblog.com)
My votes for cliff hangers:
No. 13-1314, Arizona State Legislature v. Arizona Independent Redistricting Commission (use of non-partisan commission to adopt congressional districting plan), argued March 2, 2015
No. 14-114, King v. Burwell (ACA subsidies for insurance purchased on federally created exchanges), argued March 4, 2015
My votes for nail-biters
Nos. 14-46, 47, & -49, Michigan v. EPA (and others) (EPA regulation of hazardous air pollutants from electric utilities), argued March 25, 2015
Nos. 14-556, -562, -571, & -574, Obergefell v. Hodges (and others) (challenge to state bans on same-sex marriage and recognition thereof), argued April 28, 2015