A partial list of who is acquiring, licensing, and enforcing patents:

Acacia Research Corporation
IPotential
Inflexion Point
Altitude Capital Partners
Ocean Tomo
Rembrandt IP Management
NW Patent Funding Corporation
Intellectual Ventures
Gathering2.0 (online community for monetizing IP assets)

Articles:
Patent Attorneys, Clients Banking on IP Brokerages (law.com)
Patent Pirates (forbes.com)

37 CFR 1.53(b) and 37 CFR 1.63(d) Divisional-Continuation Procedure: MPEP 201.06(c)
Claiming the Benefit of an Earlier Filing Date: MPEP 201.11
Oath or declaration: MPEP 602.05(a), 37 CFR 1.63, MPEP 201.06(c)(II)
Information Disclosure Statements: MPEP 609.02