The Dirt Devil Kone Vacumm works great.  I have three cats that are quite messy with the kitty litter.  The Kone can really get into those tight spaces where kitty litter likes to hide.  It also works well along baseboards, under cabinets, and inbetween the couch cushions.  For larger jobs just grab your broom and sweep into a pile and then suck the whole pile right up with the cone.   The battery lasts along time as long as you don't keep it charging all the time.  To do this just turn it sideways in the base until the battery is almost depleted & then place on charger correctly.