The problem with acidic soil and tomatoes is that they aren't able to take up the needed calcium to develop their skins, and so they get blossom end rot. For this reason, I wouldn't consider them a good candidate as a blueberry companion.
Azaleas and rhododendrons would work very well (although their use is limited).
I'd be tempted to try groundcovers like strawberries around them, but I'm not sure how strawberries respond to acidic soil.
