I heard/ read somewhere that "Fermat's last theorem" is named as such because it is "Fermat's last conjecture to be disposed of." This got me interested in knowing what Fermat's other conjectures are. I tried searching online but only found a handful, such as:
(1) Fermat's little theorem,
(2) Fermat polygonal number theorem, and
(3) Fermat's theorem on sums of two squares.
All the theorems mentioned above were stated by Fermat without proof, which were later proved by other mathematicians like Euler, Lagrange, Gauss, or Cauchy.
Are there any other?
For a simple search, see Fermat Biography in wikipedia and related links for related problems.
For a fundamental searche ( some times hard ) see Full MacTutor biography an related bibliographies. For a short history of Fermat conjectures see biography in encyclopedia.com. For a big list of Fermat Lattes see http://science.larouchepac.com/fermat/.