Here are some resources to help people with researching land ownership. They all take a bit of a learning curve to get used to, but are very useful if you take the time to figure them out. It's not an exhaustive list, so I hope others feel free to post additional resources.
I didn't find on-line ownership maps for any other boroughs, but the Alaska Mapper and BLM's SDMS will probably cover most areas outside of city limits in the rural boroughs. One word of caution: The BLM's generalized land status is just down to the section level, so you can't always tell how the ownership within a section is split out without going to the MTPs (master title plats), which can be pretty cryptic to read. However you can contact any Alaska Department of Natural Resources office, any BLM Public Room, or any Borough Planning and Land Management department and get assistance.
I hope this is helpful.
State of Alaska's "Alaska Mapper" (on-line mapping application - very good)
BLM land status records (many different types of records - takes tom
Fairbanks Northstar Borough GIS:
Matanuska-Susitna Borough GIS:
Municipality of Anchorage GIS: (appears to be broken at the moment)