One of the first things I do when setting up my Vim on Ubuntu is download akitaonrails' vimfiles, which has lots of cool stuff bundled. I like the dark theme that is set up (dark gray background and white foreground, and helps my sight issues).
Normally the blinking cursor is white background and black foreground. I don't really know exactly when or how it happened (maybe when I installed CommandT), but I lost the blinking cursor... I mean, I didn't lose it.. It was there... But it was invisible. And that annoys me 'cause I can't tell where I'm at in the file.
Thankfully, it's an easy recovery. Just run what I found in Vim's command mode:
highlight Cursor guifg=black guibg=white
Oh! There it is! Now I can continue working. :)
If you need anything else, I recommend the Vim Tips Wiki.