Web.com has merged the SnapNames and NameJet inventories. So when you do a search for NameJet, SnapName domains will show up, and vice versa.
Buy Reference (Science) Expired Domains
List of Expired domains in the Reference (Science) Niche
I've tried a number of expired domain finding tools and services but the support from DomCop is second to none. It's in my top two of tools to use, and the best I've used for crawling.Glen Allsopp, Gaps.com