Looks interesting, I haven't used the nbagg backend yet. I may be reducing some spectra in the next few weeks so I'll take a look at it and see if there are any modifications I can make to pyspeckit.

I've been using https://github.com/arnoutaertgeerts/python-highcharts for this. It allows you to interact with a dataset, like a spectra, in jupyter and select or zoom in to different ranges. Right now I have some ad hoc tools to calculate equivalent widths and what not but it would be nice for someone to create a package with these features built in.

Unfortunately I'm finished using this part of my code until after my thesis is finished and don't have time to refactor it. But if a GSoC student is working on this over the summer I would be happy to assist him/her so that the best pieces of both modules could be put together into a useful tool.

In astropyp I have a module that I'm working to replace SCAMP and align images using both image coordinates and WCS that is currently poorly documented but works better than SCAMP to align images from different epochs based on image coordinates (as long as the user can give two catalogs of matched sources). It uses a fairly straightforward polynomial transformation to convert the coordinates that can be used in python but does not convert the solution into a valid WCS header yet.

I also have a pull request to complete on astroquery to call Astrometry.net from python and when I have more time this fall (sorry it's taking so long to complete this Adam) these two modules combined should be a complete solution that doesn't require any software to be installed outside of astropy and affiliated packages.

I should also note that I've been working on implementing crowded field psf photometry for a while in the astropyp (astronomy pypeline) package. Unfortunately the documentation will be lacking until I graduate this summer but I've been able to get 2-5% photometry in crowded fields in Sco-Cen, which stretches across the galactic plane in the southern sky (there are some examples in the repository but some of them are out of date). I've tested it on SDSS fields taken with DECam as well as simulated photometry but have not done robust testing outside of my own data.

astropyp also has code to get an astrometric solution (without using SCAMP) and stack images (using multiprocessing) with no WCS information. Expect to see more updates and documentation in the fall when I start my postdoc. I hope that most of this will eventually get integrated into photutils and astropy but there are likely to be some higher level functions that will remain in astropyp.