vim-orgmode - Text outlining and task management for Vim based on Emacs' Org-Mode : vim online. Who wants OrgMode but finds the Emacs key layout simply sick (which could be about 99% of all VIM users), now there is also OrgMode for VIM. As a plugin. I myself mostly use VimWiki, but maybe I'll check out VimOrgMode as well, it sounds quite interesting (although I have connected VimWiki with Trunknotes to edit things on the go - but there is also an iPhone app for that).
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Tagbar, the Vim class browser. Seems to be a bit of a souped-up Taglist for VIM. Provides hierarchical views of defined classes, methods, and functions in a project.
Vundle 0.7 is out. I usually use Pathogen, but Vundle has some features that make it quite interesting - maybe I should play around with it. On the other hand, I haven't made any updates and changes to my Vim installation for a long time. But since all vim.org scripts are now on GitHub, Vundle's GitHub integration is certainly very interesting.
How to write vim plugins with python. Because I like Python, because I like Vim and because you always want to build smaller things that make life easier. And because Vim's own scripting language is rather awful.
Who is used to Vi and uses Chrome: Vimium provides Vi-like keyboard control for Chrome. After a short period of getting used to it, it is really very useful and can significantly help in reducing the strain on the mouse hand.
slimv.vim - SLIME-like Lisp and Clojure REPL inside Vim with Profiling, Hyperspec, Paredit. Quite interesting, as it is much lighter and simpler to install than Slime or VimClojure or one of the other heavy solutions. And you can simply program Common Lisp or Clojure from within Vim. It is currently only in the "playing around and looking" mode, but it sounds quite interesting.
Gundo - Visualize your Vim Undo Tree. Vim does have a bit more to offer when it comes to undo than usual editors - the entire tree of undo/do/redo actions is stored and you can move freely within it. However, no one really understands this with the normal Vim means. With the Gundo plugin, you can directly visualize this tree and perhaps make sense of it. Sure, you can achieve something similar through regular commits and version control. And of course, we all commit early and often and never have any long editing sessions, right?
snipMate - TextMate-style snippets for Vim : vim online - since I'm just listing things that aren't really interesting to me but are still somehow cool, here's an implementation of TextMate-like snippets for Vim.
vcscommand.vim - CVS/SVN/SVK/git/hg/bzr integration plugin : vim online - something I'd rather do in a shell than in the editor. Mainly because I rarely have single-file commits. But for querying history, it could still be interesting. It's also one of the more active Vim plugins - some of them are really shockingly old, but still work well. One plugin even had a reference to its homepage at GeoCities ...
pyclewn. Not sure if I want to dive into this - I don't usually use debuggers. But this one is integrated into Vim and thus directly usable from the editor. gdb and pdb (for Python) can be used.
Vim Taglist plugin manual. Another important component to be able to work properly with MacVim. It is also recommended to install exuberant-ctags with brew install ctags if you want to use real languages (such as Python).
Vim autocomplete, Django and virtualenv | rosemanblog. Especially the integration of VirtualEnv and MacVim is helpful, because otherwise Omnicomplete does not work cleanly with VirtualEnv, as it knows nothing about the modules located there. By the way, installing MacVim with Homebrew is trivial ...
agr / ropevim / source – Bitbucket. There is also a Vim integration for the other tool that interested me about Spyder: Rope. A refactoring tool for Python code. Not entirely uninteresting for a sufficiently large code base.
pyflakes.vim - PyFlakes on-the-fly Python code checking : vim online. I'm also looking at this right now, as it provides some interesting tools for Python and is quite good to use, especially with MacVim.
xmledit - A filetype plugin to help edit XML, HTML, and SGML documents : vim online - nice plugin for VIM (more precisely a macro package) to better edit XML files with tag completion and automatic closing and jumping between block start and end.