I have run across a number of them, and welcome other examples:
(1) bolster your IT support (See my post of Oct. 22, 2005 about managers from both sides meeting.),
(2) provide access to documents (See my post of Oct. 31, 2005 about JennerNet.),
(3) offer CLE training,
(4) provide secondees (See my post of Sept. 21, 2005 about secondments.),
(5) set up extranets (See my post of Jan. 3, 2006 about Shook Hardy and Oct. 21, 2005 about a Minnesota firm’s offerings.)
(6) recruit jointly, such as did Orrick Harrington and Lucent Technologies several years ago, and
(7) track contracts (See my post of April 27, 2006.)