Is there som method of "linking" or referencing items that are in the database?
Up to now, no. It’s on our (very long) to-do-list, though ;)
I’m working on several projects for which the addition of both true external file links AND links to other DEVONthink content pages would make my life much easier.
I’ve just come across a new Cocoa application, Voodoo, that thrives on hyperlinking – see flyingmeat.com/voodoopad.html – for both external files and Web URLs.
For the moment, I’m using Voodoo to make project notes that include hyperlinks to external files. That works great. I can set up a set of Voodoo notes that refer to specific external files used in my DT database, including notes, comments, excerpts, etc.
Wouldn’t it be nice, also, to include links to DT content pages, or link DT content pages to each other? I can’t directly do that with Voodoo. BUT I can include in Voodoo notes either the Names of DT content pages, or unique words or phrases – so that I can highligh the word or phrase, press Command-/, and use DT Search to quickly find the DT content I’m referencing. (Of course, I can already do that within DT content, as well.)
I can then copy the UNIX path of the topmost Voodoo note page, create a new content in DT, past the UNIX path into the Info for the new DT content, and am then able to launch my Voodoo note set from within DT.
This set of workarounds is awkward, clumsy and not completely satisfactory. But it partially fills an unmet need for using DT.
Please raise the priority for adding both external file links and internal content links to DT!
Happy DEVONthink user
I just want to add my vote to those requesting internal linking.
I just wasted a bunch of time figuring out that I simply couldn’t do it. That old Mac-user intuition just screamed that it should be doable somehow, so I kept on trying to drag&drop documents into other documents, holding down command, option, control, shift as I did so… darn things just kept bouncing right back out again >:(
"Link, darnit, link!!" she muttered feverishly…
Well, at least it inspred me download a fresh new version and to thoroughly peruse the nice new pdf docs. 
Noel
One more vote in this direction.
Thanks.
Linking DT items together – yes please! And preferably in multiple modes:
Item to Item (uni - or bi-directional)
Item to word or phrase within same or other item (ditto)
And both of these on a one-to-many (or many-to-one) basis.
This would need a "browse links" command to be really useful. But even a basic item-to-item manual link would be excellent.
while we’re at it…how about making them wiki style links
This will come - maybe in v1.8 but probably in v2.0. Most important improvements of v1.8 will be a contextual menu plugin, synchronization, revised searching and improved outlining (manual sorting, OPML im/export etc.). Most important improvements of v1.7.4 (coming before X-mas) are WebKit integration and finally stable column views again.
I second this vote – I think that linking and sync are the too most important missing features in the application right now. To my mind it is just not really possible to take active notes in DT until there is Wiki-style linking. Wiki linking a) makes you write in a more organized, topical way; b) does your searching for you as you write; and c) gives you a lot of options as far as groups, since you can then keep your ‘groups’ in text documents that you modify at will.
Version 1.7.6 will introduce "Cross Links" (static) and Wiki-style links (dynamic) to contents/groups. And there will be a handy "See >Clicked Word<" contextual menu command too.