Nat, my suggestions would be for newborns, baby swings, I have layby'd the fisher price one in target as it locks still and has vibrating action too. DS would always fall asleep in the swing and would wake up when it stopped. Great for making dinner though or something. Then from about 5 months, the best thing ever is the jumperoo! (I have also layby'd this too at target!) they get frustrated cos they want to be in a more upright position and are still a bit wobbly. This lets them kick their legs around and it's hours of fun. DS used his for quite a while too, even when he was starting to walk I could put him in this and know where he was!
Hope that helps! x