I use textbooks less and less in my teaching now, and I find that the exercises in most new textbooks aren't great for what I want out of the lesson. If I want basic skills practice, there's often bits in there I don't want the pupils doing (such as a substitution exercise which uses negative numbers before they've been taught this), and then there's the irritating bit of explaining that they need to start on Q3 and do up to Q5, then move on to Q21 on the next page, and it's all more trouble than it's worth. And let's not talk about having to hand the flipping things out...
So here's my top 5 sites for basic practice worksheets - you're not going to get any stunningly engaging resources here, but sometimes teaching is more important than entertainment.
I completely agree that sometimes students just need to practice a skill with no distractions. Making lessons engaging and "whizz-bang" is great, but they do not always get the necessary practice from these. I created a set of Worksheet Generators for this reason to use in my class, which you might like too http://www.interactive-maths.com/qqi-worksheets-index.html. Thanks for these recommendations, I had not seen Worksheet Math before.
I run WorksheetMath, and just came along to say thanks for the mention!