In the consumer good industry, your best bet is to be contextually relevant and meet the customer half way. I like cross selling like anyone else, but complimentary sales strategies are doubly effective.
TROJAN (condoms) next to baby food, as in “While you’re in this aisle, how about this mistake prevention mechanism?”
M&M’s in the feminine hygiene aisle, as in, “You might want to get here these as well and get bonus points for caring.”
Invest in conversion* marketing, points of sale data and shopper marketing. Raise awareness by engaging your target customer around a common cause or interest point – all positive.
Got any more ideas?