So your going with a semi aggressive type tank?
Your definitely not going to want anything like an angel or gourami or even guppies. As the Tiger's will rip them to shreds.
Try going with another type of barb. And I'd also add 5 more tiger's to spread out the aggression more.
Cherry Barbs are wonderful fish. I have 6 in a 55 with non aggressive fish and they are gorgeous.
They aren't at all aggressive, but would work really well in a semi aggressive tank. 10 them would be just amazing.
The females are a burnt orange color, they're pretty cute. The males however are a vibrant red. The males don't fight with each other like some other species so if you only wanted males or even just females you'd be fine.
A red tailed shark would be cool also. I have one in my 55, and it's one of my favorite fish I've ever had. They have a nice temperament in general, and would be ok with all the barbs. Mine has never been a problem. They look super dull in the stores but have no fear once they come home and get settled their true colors come out literally. :]
They have a beautiful black body with a bright red tail. They aren't actually of the shark genus at all but rather a catfish.
However they CAN NOT be kept with any other type of shark. They fight, and well the situation wouldn't be very pretty. (Your cat should be fine with the shark so no worries..I keep plecos with mine)
Besides those I can't think of what else to add. You could try a school of tetra's but I'd be cautious because I know how tiger's are.
Well good luck :] and happy fishing
