I use HandyRad (http://www.handyrad.com/). You can add and update your cases at any time and location (with internet access). It also allows to upload images for your interesting cases and to create teaching files. There are others such as Radiology Teacher (published in last Dec. issue of JACR) which are primarily teaching file servers like MyPacs but Radiology Teacher can be also used for tracking.
Another system is MIRC (http://mirc.rsna.org/), but pretty cumbersome to handle. I don't know ANY radiologist (normal/mortal radiologist who does not think in bits and bytes) who has ever accomplished to install MIRC on his/her own.
You asked for something that "plugs into ge centricity". Virtually impossible unless you can hack yourself into the PACS or the PACS vendor itself permits access of third party programs into its structure.