A common problem I find among university students is difficulty reading quickly or efficiently. Reading problems can also occur in conjunction with depression.
The best thing to do to improve reading skills is, of course, to read more. But a phenomenon which often happens when reading any text, but especially longer texts, such as novels, is that you can lose track of what you have just been reading. Whole sections of the text may end up being skimmed superficially, as part of your attention lapses or wanders, while still maintaining a basic pace of absent-minded reading. This leads to a lack of enjoyment or feeling of mastery with reading, dampened morale, sapped motivation, contributing further to any depression which had been present, and deterring further reading efforts.
An approach to this type of problem requires you to stop to reflect or answer questions frequently about what you have just read. Whenever you test yourself regularly, your learning and retention are greatly increased. Most good introductory university textbooks are set up this way. But not very much in the line of non-textbook reading.
So, I have been trying to find resources to help with reading skill, for adults. Elementary-school language textbooks or readers seemed like a reasonable thing to check. I certainly recommend that adults at least periodically read books which have been written for children or adolescents. The best things I've found online are from ESL (English as a second language) programs. Even if you are an advanced reader, or have spoken English all your life, I think that ESL exercises could be good for improving reading skill.
Cognitive-skills training websites tend not to offer very much in terms of language learning or improving reading fluency or retention. I wish that the cognitive skills website people could develop more along these lines: reading-oriented games don't seem very difficult to imagine or design, compared to other types of games.
Here's a list of a few sites I've found, where you can practice English reading skills:
This is an excellent free resource from the University of Victoria (in BC). For the reading exercises, choose an "English language level" (beginner to advanced), then follow the links about reading.
Houghton Mifflin College
This site also offers timed readings with questions afterwards.
Quizzes Based On VOA Programs (ESL/EFL)
This link goes to a site where you have to read a text a sentence at a time, and fill in the blanks from a list of options, according to what makes sense or is grammatically correct. While some might find this type of exercise too easy, I think it is a nice way to remain more interactive with the text. If you do find it easy, you can just try to do it faster, and make it into a game.
Another useful thing to look for is an online book club which has discussion questions about the book you're reading. Some sites have questions for each chapter, which is the type of thing I'm recommending, so that you can pause frequently to review what you have just been reading. I haven't found a single site which has chapter-by-chapter questions for a wide variety of books, but here's an example of a specific site, giving questions about Great Expectations by Charles Dickens (a great book, by the way):