Tips and advice on how to clone Textmate's functionality in Ubuntu. I've done some research on this in the past and I know this information is valuable to the community.
For Textmate style snippet expansion in Vim.
The Command-T plugin is un-do-without-able. It replicates TextMate's Go To File... functionality very nicely, plus of course you can set your own keymapping, and have files open in split windows, tabs, etc.
For file exploration in Vim.
If vim is not a requirement (in the title you said Vim but in the text you said how to clone textmate in ubuntu) you should take a shot on emacs.
In emacs you can have a closer textmate experience, with a snap-open (ido-mode) snippets with yasnippet (compatible with textmate snippets) and an editing style a little closer to what you get on textmate.
try this Coming Home To Vim
Replicate TextMate's bundle functionality. After installing pathogen, you can drop plugins into a 'bundle' directory, pathogen manipulates vim's runtimepath so everything gets loaded.
This is especially great for using vim plugins which live on github. If you keep your config in a git repo, you can use submodules to help you keep everything up to date.