Showing off a large astro mosaic these days is not easy, given that the files can be huge with some great detail. Recently I did an 8 pane mosaic of the terminator region on the 11th April 2014, each pane approx 1280960 pixels, so you can imagine that the file size can start to get big once stitched together.
I find that the Microsoft Zoom.it website to be the best to show off the image, Ive used it twice now and plan to use it in the future once I do a full lunar disc mosaic. The good thing with Microsoft ICE is that it is very easy to zoom in and out and scroll around the image, also its FREE.
To merge the mosaic I used a combination of PixInsight and Microsoft ICE (as I had trouble merging some panes with just one piece of software). This removes the gradient differences / joins that you would normally see where the panes connect. I then published the TIF file on my webspace and provided Zoom.it a link to it so it could do its thing.