I need fluorescence spectra for various fluorophores in certain dispersion media for some calculations. There is an online database of University of Arizona: http://www.spectra.arizona.edu/ Is using such online resources reliable (not for formal purposes)? I'm sorry for not asking a technical chemistry question.
That is the correct domain name for the respected and accredited University of Arizona. I would feel confident using their data.
In general, that's the key: being certain that the source is who they say they are, and that they are a source that you have some reason to trust.
Regarding security, it's unlikely someone would spend the time, money and effort required to falsify some fluorescence spectra database. If it were a database of controversial climate data, or clinical trials for a new medication, etc., you might want to investigate what the site does to secure their data.
I would also be cautious of using open wiki data like Wikipedia. Although I've personally gotten into the habit of trusting those sites more than I should, anybody can edit them. And while they try to police the sites for poorly documented data and such, it's a lot to keep up with. A good wiki article will have sources for their data, and reaching out directly to the source, if possible, is the better way of getting reliable data from a wiki site.
As airhuff already pointed out, the origin of the database is the University of Arizona. The data was compiled by Urs Utzinger, who seemingly still holds a position there in biomedical engineering.
I can't comment on the Flash part, since I do not use Flash.
The SQL dump, which can be used to recreate the database, contains lots of information on the data sources for the different spectra.
In summary, I would trust the data.