How can I find out which known stars lie within or close to M8 I'm looking for a way to find stars within a certain region of space, the Lagoona Nebula in this case, based on what we currently know. Are there some databases that allow you to make such queries?

Please note that I'm not looking for stars that can be seen as being near M8 from earth, but for a list of known stars that are thought to actually be near or part of M8 itself.
Have a look at the following references - found relatively easily using the following query in the NASA ADS site.

UBVRI and Hα Photometry of the Young Open Cluster NGC 6530
This paper by Sung &amp; Bessell (2000) contains an extensive photometric catalogue. The main table can be queried interactively.

The Lagoon Nebula and its Vicinity
This is a review article by Tothill et al. (2008), from which you can get pointers to most of the significant literature (pre-2008) on the region.