Not so much fish you should never put with them, but more a point about the number of tiger barbs with whatever fish you want to put them with.
As you may or may not be aware, Tiger Barbs are notorious fin nippers. If you put 2 TB's in with a shoal of 16 Tetras, they are going to chase and nip them. However, if you put 2 Tetras with a shoal of 16 TB's the theory is that the TB's will be preoccupied with checking on where the other TB's are. Realisticly i hope nobody puts that many TB's with that many Tetras anyway, but its an example.
Providing there are enough TB's to keep each other in check (7+, i prefere 9+), then you should be ok keeping them with most fish. There are exceptions, like perhaps shrimp arent advisable, or harlequin rasboras because of their size. Betta's are probably a bad choice due to their long finnage.
Be sensible with stocking and TB's are very fun fish to keep. I wish i didnt have to let mine go, but other fish were a higher priority to keep.
James