Every studio should have at least one Bleeplabs Thingamagoop. They cost a bit more than a lava lamp but the smile factor is way higher on the yay scale. You can customize your Thingamagoop to look like no other. They run off a 9V battery and are kind of like weird cute bleeping Theramins.
“The Thingamagoops are really just simple, analog type synthesizers that you control in a different way.” – bleeplabs.com
Thingamagoops are $120. For more info: http://bleeplabs.com/