These sites cover basic fact practice and addition /subtraction with regrouping.
BASIC ADDITION FACTS http://www.harcourtschool.com/activity/add/add.html
BASIC ADDITION FACTS http://aplusmath.com/games/picture/AddPicture.html
SUMS TO 20 http://www.bbc.co.uk/schools/ks2bitesize/maths/activities/addition.shtml
BASIC ADDITION http://www.bbc.co.uk/schools/laac/numbers/chi.shtml
ADDITION OF 3 NUMBERS WITH REGROUPING (A recording sheet can be printed.) http://www.harcourtschool.com/activity/elab2004/gr3/3.html
NUMBER LINE ADDITION http://www.harcourtschool.com/activity/mmath/mmath_lion.html
TENS & ONES - BEGINNING REGROUPING http://www.edbydesign.com/btcount.html
BASIC SUBTRACTION FACTS http://aplusmath.com/games/picture/SubPicture.html
BASIC SUBTRACTION FACTS http://www.arcademicskillbuilders.com/games/mission/mission.html
BASIC ADDITION & SUBTRACTION FACTS http://www.harcourtschool.com/activity/thats_a_fact/english_K_3.html
BASIC ADDITION & SUBTRACTION FACTS http://www.playkidsgames.com/games/mathfact/mathFact.htm
ADDITION AND SUBTRACTION PROBLEMS- VIRTUAL CALCULATOR http://www.hbschool.com/activity/calculator_gr1/
CLICK on BASE BLOCK ADDITION or BASE BLOCK SUBTRACTION http://nlvm.usu.edu/en/nav/category_g_2_t_1.html
ADDING AND SUBTRACTING WITH SAME NUMBER - THREE LEVELS http://l3d.cs.colorado.edu/~dodsonc/CaveMaze/index.htm
REGROUPING - PLACE VALUE BLOCKS http://www.arcytech.org/java/b10blocks/b10blocks.html
ADDITION & SUBTRACTION AT 3 LEVELS. http://www.playkidsgames.com/games/shuttleLaunch/shuttleLaunch.htm