Great thread, Lommy!
Let me add my share of German names (far from complete, just the ones I found interesting):
The Fellowship
Frodo Baggins (Underhill) ~ Frodo Beutlin (Unterberg) (Beutel=bag. Just like in English, one would expect there to be a 'g' after the 'n', which is also omitted in the German translation)
Samwise Gamgee ~ Samweis Gamdschie
Meriadoc (Merry) Brandybuck ~ Meriadoc (Merry) Brandybock
Peregrin (Pippin) Took ~ Peregrin (Pippin) Tuk
Gandalf
Aragorn (Strider) ~ Aragorn (Streicher) (Streicher doesn't mean much, but it reminds one of Landstreicher=vagabond, which I think is slightly disrespectful
)
Legolas Greenleaf ~ Legolas Grünblatt
Gimli son of Glóin ~ Gimli Glóinssohn (not sure why they changed this, it makes it sound Scandinavian)
Boromir
Other people
Barliman Butterbur ~ Gerstenmann Butterblüm
Barrow-wight ~ Grabwicht
Bill Ferny ~ Lutz Farnrich (the pony Bill is also called Lutz)
Goldberry ~ Goldbeere
Gríma Wormtongue ~ Gríma Schlangenzunge (like in Finnish, Gríma has the tongue of a snake over here)
Grishnákh ~ Grischnách
Lobelia Sackville-Baggins ~ Lobelia Sackheim-Beutlin
Old Man Willow ~ Alter Weidenmann
Quickbeam ~ Flinkbaum
Rose Cotton ~ Rosie Kattun
Shadowfax ~ Schattenfell
Sharkey ~ Scharker
Shelob ~ Kankra (a Kanker is a sort of spider and the 'ra' makes it sound feminine. I think this is not a good translation of the name. The sounds of the two are just too different)
Ted Sandyman ~ Timm Sandigmann
Thórin Oakenshield ~ Thórin Eichenschild
Treebeard ~ Baumbart
Witch King ~ Hexenkönig
Geographic names
Bag End ~ Beutelsend
Bagshot Row ~ Beutelhaldenweg
Barrow-downs ~ Hügelgräberhöhen
Buckland ~ Bockland
Dead Marshes ~ Totensümpfe
Dunharrow ~ Dunharg
Grey Havens ~ Graue Anfurten
Helm's Deep ~ Helms Klamm
Hobbiton ~ Hobbingen
Lonely Mountain ~ Einsamer Berg
Middle-earth ~ Mittelerde
Mirkwood ~ Düsterwald
Misty Mountains ~ Nebelgebirge
Mount Doom ~ Schicksalsberg
Rivendell ~ Bruchtal
Shire ~ Auenland
Weathertop ~ Wetterspitze
Westernesse ~ Westernis
Various geographic names
Ashen Mountains ~ Aschengebirge
Brandy Hall ~ Brandyschloss (which makes it Brandy Castle)
Brandywine ~ Brandywein
Brown Lands ~ Braune Lande
Bucklebury ~ Bockenburg
Bywater ~ Wasserau
Crickhollow ~ Krickloch
Dale ~ Thal
Deadmen's Dike ~ Totendeich
Dimrill Dale ~ Schattenbachtal
Entwash ~ Entwasser
Ettenmoors ~ Ettenöden
Gap of Rohan ~ Pforte von Rohan
Gladden Fields ~ Schwertelfelder
Glittering Caves ~ Glitzernde Grotten
Hollin ~ Hulsten
Isenmouthe ~ Isenmaul
Lake Evendim ~ Abendrotsee
Loudwater ~ Lautwasser
Michel Delving ~ Michelbinge
Midgewater Marshes ~ Mückenwassermoore
Mirrormere ~ Spiegelsee
Old Forest ~ Alter Wald
Redhorn ~ Rothorn
Stonewain Valley ~ Steinkarrental
Wellinghall ~ Quellhall
Things that don't fit elsewhere
Dwarf ~ Zwerg
Easterling ~ Ostling
Elf ~ Elb (this is interesting, since the word "Elf" exists in German as well. As far as I know, Tolkien himself suggested this change, so that, at least in German, people wouldn't be reminded of fairy-tale Elves)
Fallohides ~ Fahlhäute
Harfoots ~ Harfüße
Neeker-breeker ~ Niiikerzriiiker (now, this one is just terrible
)
Oliphaunt ~ Olifant
Ringwraith ~ Ringgeist
Southron ~ Südländer
Stoors ~ Starre
Wizard ~ Zauberer
All these names are from the second translation, which is said to be the worse one (but how could I have known back then?). Maybe there are differences to the old one.