SchH (including levels SchH1, SchH2, SchH3) - Schutzhund, a dogsport with three separate phases Tracking Obedience and Protection. Originally formed as a breed suitability test for the German Shepherd Dog, in Germany in the 1920's. It is the most popular dogsport in the world as per numbers. There are several sanctioning bodies that hold trials, issue scorebooks, etc.
USA - United Schutzhund Clubs of America - the biggest Schutzhund sanctioning body in the United States currently. It is actually the German Shepherd breed club in the U.S., although they do allow other breeds to compete and achieve titles in club and regional trials.
http://www.germanshepherddog.com
DVG - Dutscher Verband der Gebrauchshundesportvereine. The other "major" sanctioning body for Schutzhund in the United States, touted as the all-breed schutzhund club. It is overseen in Germany.
http://www.dvgamerica.com at their website there is a great deal of information on the titles and rules to attain them.
VPG - Vielseitigkeitspruefung fuer Gebrauchshunde meaning "Versatility Test for working dogs" another name for SchH title, changed about 3 years ago. Just to add some more acronyms for us;)
IPO - don't know what is stands for honestly - again, same as a SchH title under international rules (bascially the same as DVG, USA, etc). The FCI's name for the title.
FH - literally "tracking dog" a test through the aforementioned sanctioning bodies, that is only tracking and more challenging than even the SchH3 track - at least 1200 paces, aged 3 hours, through varied terrain, with 4 articles that the dog must find. There is the FH1, and the more difficult FH2.
WH - another test "basic protection" or watchdog title.
AD - endurance test, where the handler bikes with the dog, for 12.4 miles.
RH - search dog suitability test.
BH "Begleithund" - translated "companion dog", a temperament and basic obedience test that must be passed before entering any trial for a bitework title (in Schutzhund).
I have only attempted to list the Schutzhund-related titles here! And I apologize to any Germans, not all titles or spelled out. Now off to take care of the dogs:)