Abstract: In some embodiments, the present invention provides methods and systems for facilitating transactions between advertisers and advertisees for arranging for presentation of advertisements to users of computers or other computerized devices. Advertiser and advertisee offers, including user context conditions, are obtained. User context information is obtained, such as real-time or almost real-time information about an online user of an Internet site of the advertiser. If a match is determined between an advertiser offer, an advertisee offer, and a user context, arranging for presentation of an advertisement to the user is facilitated.