I've released a beta version of DX ToolBox, 4.7.0b1, which includes a new window, one for displaying a list of longwave NDB (Non Directional Beacon) stations.
Enter in a frequency, and you see a list of all beacons on that frequency, along with the pertinent information. It uses the "export_RNA.xls" database file that you can download from the RNA site:
http://www.classaxe.com/dx/ndb/rna(Click the All RNA > Excel button at the bottom of that page to get a fresh copy of the file, which is actually not an Excel file, but rather html) Make sure you keep the "export_RNA.xls" with the DX ToolBox app, if you move files around on your computer.
As with other parts of DX ToolBox, support for the SdrDx SDR app is also included. The NDB window will track frequency along with SdrDx, and you can change the tuned frequency in SdrDx from the window.
Available for Mac and Windows, I've not done extensive testing with Windows yet, so let me know how it goes.