The student readings above contain most of what I use in my class. Add to this your own classroom text.
Corcoran, Clyde; Delvin, John; Gaughan,Edward; Johnson, David; Wisner Robert. Scott Foresman and Co. 1977. Algebra I Contains a great set of problems sprinkled throughout the text under the labels of “Take A Break”.
Games A publication of Playboy Enterprises is an interesting new magazine on the market. It can be read by all levels of students. I would use it to get the students attention and then use other more serious sources to more fully develop their problem solving powers.
Brownstein, Samuel; Weiner, Mitchel Barron’s How To Prepare For College Entrance Examinations 4th Ed 1969 An old but very useful series of problems I would suggest a more recent edition of the work.
Raudesepp, Eugene “More Creative Gamesmanship” an article from Psychology Today July 1980