With mURL you combine several bookmark (URL) files into one mURL (multi-URL) bookmark.
Just double-click the mURL bookmark file to open all the URLs that it contains. Each will open in its own window.
In the options dialog of mURLin, choose how you want your mURLin bookmark to be saved. Drag-and-drop as many bookmark files as you want onto the mURLin icon to create one multi-URL mURLin bookmark file.
mURLin has two versions, one for use with Internet Explorer, and one for use with Netscape Communicator.
On the first run, you may be asked for the location of your browser. If drag-and-drop to the icon doesn't work, try rebuilding your desktop file (restart while holding command option). mURLin has been tested with browsers 4.0 and above only.