All of us are looking for business contacts on a daily basis to fuel our outreach efforts. There's an easy way to find contact lists (deeply) hidden in site maps, courtesy of Google.
It's a trial & error process but it usually delivers an unexpected trove of valuable contacts. I discovered this opportunity purely by accident while cross-checking the validity of a recipient.
Choose a few valid email addresses of contacts belonging to the groups you want to target. Then type these queries into Google search bar (firstname.lastname@example.org = the valid email address).
email@example.com filetype:xls (or filetype:pdf)
Google will instantly display a series of indexed excel files (or PDF files) which contain the email you've used as a reference. Very often the results are lists compiled on the occasion of a professional event / conference.
Here is for instance a PDF you can find on Noah's conference website, in their media section (You'll notice that the emails of the contacts are white on white in this PDF): https://www.noah-conference.com/media/NOAH15-SpeakerBook(June).pdf
Instead of a specific email address, you can also use strings like @domain.com to find documents containing an occurence feat. a given domain.