Quadratic assignment problem
Vehicle routing problem also at HEC
Quantified Boolean formulas
Mixed integer programming
Set covering and packing
Beasley's OR library with many problems
Maximum clique, Maximum independent set, minimum vertex cover, vertex coloring
Here is a start. Please add to this.
BOLIB: Bilevel Optimization LIBrary of Test Problems https://eprints.soton.ac.uk/436854/1/BOLIBver2.pdf
CBLIB: The Conic Benchmark Library: http://cblib.zib.de/ . Twitter at https://twitter.com/cblibtw
COMPlib: COnstraint Matrix-optimization Problem library (Nonlinear SDPs, control system design, and related problems) ...
Some more libraries:
Biq Mac Library: a Binary quadratic and max cut Library: http://biqmac.uni-klu.ac.at/biqmaclib.html
OR Library: a collection of test data sets for a variety of Operations Research problems: http://people.brunel.ac.uk/~mastjjb/jeb/info.html
SIPLIB: a collection of stochastic integer programming problems: https://www2.isye.gatech.edu/~...
Atamturk datasets on fixed-charge flow, lot sizing, mixed-integer knapsack, and more
Combinatorial Auction Test Suite (CATS)
National Traveling Salesman Problems
VLSI data sets: Another collection of 102 TSP instances
GiC Data Sets
Update: I made a GitHub repository and added all of these references. there.
Some libraries for stochastic programming test problems may be found in
Jeff Linderoth, Alex Shapiro, and Stephen Wright (2002)
POSTS: A (PO)rtable (S)tochastic programming (T)est (S)et (Derek Holmes and John Birge)
Test-Problem Collection for Stochastic Linear Programming (Andy Felt)
SIPLIB: A (S)tochastic (I)nteger (P)rogramming Test Problem (LIB)rary (...
Would these be helpful?
1) OptaPlanner examples problem definitions and data sets
Original problems: cloud balancing, dinner party, tennis club scheduling, meeting scheduling, task assigning, investment portfolio optimization, conference scheduling, rock tour, flight crew scheduling
Problems defined by academic challenges and others: tsp, course scheduling ...