Firms that specialize in recovering payments from class action defendants on behalf of claimants or, in their stead, as assignees have created a small niche. According to an interesting article in Corp. Counsel, June 2006 at A7 (James Morsch), such firms either offer to handle the claims filing in return for some percentage of the amount distributed or persuade the class action member to assign their claim to the firm for a payment.
The costs to a company of a class action settlement will undoubtedly rise if the recovery firms succeed in rounding up or taking over claims, since payments will therefore increase. One I found online is Spectrum Settlement Recovery.