The International House of Prayer in Kansas City, Missouri, has worship and prayer 24 hours per day. They now have free live web streaming from their prayer room. Go to www.ihop.org and click on The Prayer Room.
Be forewarned: There are many styles of worship – some are quite contemplative and some very upbeat. If you check the schedule I think Worship in the Word hours are more quiet while Intercession Hours are more loud in general.
To me it is neat to know that 24 hours a day I can join with other brothers and sisters in the Lord and be refreshed by His Spirit. If you are ever going through Kansas City, IHOP can be a refreshing place to stop.