Cedric has done a fantastic job creating Doclipse, an Eclipse plugin that gives code-completion for doclet tags, including XDoclet-style tags.
I think I like Doclipse more than the JBossIDE, primarily because Doclipse is much simpler, giving me only the functionality that I want, without the extra stuff for starting/stopping JBoss. Also, I managed to get Doclipse to work quite painlessly (something I can't say for JBossIDE).
Only one thing, though: I like that the required attributes are placed in the code for me, but it'd be nice if Doclipse would notice the tag context where the cursor is and allow me to use code completion to summon up the other attributes, too. Oh well, I'm sure Cedric's working on it as I write this.
Although Ryan has already provided Cedric with a Doclipse tag file for XDoclet's Hibernate module, I decided it would be nice to provide Doclipse support for all of XDoclet's modules.
So, I wrote a quick-n-dirty XSLT (took me all of 5 minutes to write) that transforms XDoclet's own xtags.xml (used for generating XDoclet's documentation) into Doclipse tag files. You can download the Doclipse tag files (including the XSLT) here. This includes all of XDoclet's modules as of XDoclet 1.2.1.