https://www.hackerrank.com/domains

This site is a series of well categorized problems.  You have the option of solving the problems in their online compiler and building up a history of work, but you would need to make an account on their site to do that.  You can always just sort through the problems and solve them in Visual Studio locally.

http://rosalind.info/problems/locations/

These are bioinformatics themed problems.  The site is built expecting you to solve the problems using Python, but again you could just look through the problem descriptions and work in Visual Studio with out tracking your work online.