Has anybody tried extending the completion mechanism of dabbrev-expand to support different sorts of completion mechanism (defined in minibuffer.el)? I know of mdabbrev-expand but it only does in-symbol completion and its incomplete for example with respect to symbol characters in emacs-lisp-mode.
By default, Icicles binds command icicle-dabbrev-completion to whatever keys standard dabbrev-completion is bound to -- typically C-M-/.
When there is only a single matching candidate, Icicles adds nothing to the party in this case. But when there is more than one possibility icicle-dabbrev-completion lets you use several kinds of completion matching.
In particular, you can use apropos completion, which means regexp matching (including substring matching). You can also use progressive completion and various kinds of fuzzy completion (in addition to the vanilla completion styles in minibuffer.el).