TimezAttack really helped DD in Yr4 (and DS in Yr1 at the time and not wanting to be left out!) - computer-style game that uses lots of repetition and builds gradually. Basic game is free and there is plenty there to keep them going. Does need quite a bit of space though so only worked on DH's newish laptop.
Two other tricks we use are: - Choose a times table and say it through once on way to school. That's 5 times in a week and it seems to help - Get two 12-sided dice (games-playing geek DH had them already but good games shops or online). Start by getting DS to choose a table, roll dice and he has to do that sum. Sometimes get easy ones, sometimes harder ones. Only need to do 4 or 5 at a time but keep dice on table and do it most mealtimes. Once he is more confident you can introduce the other dice, roll both of them and get him to do the sum that comes up.
Can do the above with two (or possibly more) DC at once, they just get to choose different tables.