there is a system especially designed for abstractors called QuestXPress.  Not only can you index by addresses, but by your file number, your client's file number, name, county, etc...
It is a web-based system so no matter where you are you can go on-line and have access to your files.  Your clients can also have limited access to the scanned images, you can then also e-mail your files and your clients can also order on-line and check status.
Go to http://www.questxpress.com/ for more information and the guys there will help you out.
Jay