Nevada is another one of the western states with some land mass, but a relatively low population. It also only has 16 counties and one independent city, so if online resources are found, they will be included in this list.
The very first stop on your visit to Nevada records must be the FamilySearch research wiki for Nevada. The reason for this is that there are a number of extinct counties that might hold records you are seeking. Some of those counties were in Utah and New Mexico, so understanding the history of Nevada is critical for research success. Scroll down the wiki page past the county map and current county list until you see extinct/former counties.
GenWed – Free Nevada marriage records online
Linkpendium – Nevada – There are both statewide links and links to individual counties here. Free to us.
Clark County USGenWeb
There appear to be a number of (mostly historical) societies in Nevada that have no website. If you are researching a particular county, take a minute to see if there is a society with a street address and/or phone number.
Nevada Historical Society