My 5th grade daughter and I started working on an online service that I found, www.TenMarks.com, last night. It's FANTASTIC! We went through all the orientation videos, and she started her first set of worksheets. At first, she was unsure how to proceed, but then we watched the video that corresponded to the concept, and she was off to the races. She scored well, and was full of a sense of accomplishment.
I'm so grateful to have found this! I was considering Kumon or the Russian Math School, both of which are huge operations in the Boston area, but TenMarks is going to suit our family so much better.
Definitely check it out! Its free to try.