Now if you actually printed large (huge?) format posters of the star chart you would have a market.
People would love to print a start chart as visible in a specific special place and time. It would be a great gift for weddings, birthdays, graduation, etc.
Less space than a Nomad, no wireless. Lame.
For those who don't get it, this is the slashdot review when Apple released the iPod. It's fair to say that the techies with their feature lists completely mispredicted the biggest music player of the decade.
Likewise, just because you as a programmer can do something like "just use a programme", doesn't mean that everyone can do it. There are people out there who can't "just use a programme"
A preview, as said by other user, would be good (and also the free share-on-FB feature could be useful to spread the word of your site)
There are some professional astronomers blogging over there, doing divulgation. They might be interested. At the very least, they will link the site.
IMHO, greaterskies.com is interesting as a project, but:
- I don't think anyone will pay for simple visual star charts: there are free sites, free desktop programs and free tablet/mobile apps out there.
- If not for visual, but deep sky: there is 3Atlas from José R. Torres (9, 11 and 13 mag sky atlas): http://www.uv.es/jrtorres/tools.html Available for free in PDF.
- The marketing problem: find your tribe! There are some forums, like cloudynights.com (or http://www.asociacionhubble.org/portal/index.php/foro in Spanish), but this are mostly for dedicated observers.
My 2 cents.
Yes customization is good, but just the star chart itself would be a cool present for a kid.