I wouldn't send too many review units out for free. Big press should have a budget to just buy a unit. Small press is nice, but sending each little blog a free unit will probably cost more than the additional orders it generates.
Suggesting blogs, magazines, websites to do a review: YES, good idea. And it might actually be better if the suggestions are made by community members and not the OPT. Sending them free review units: not such a good idea imo.