Data entry & research. Used to spend hours for lists, contact information, etc. Can be done automatically. Lead sourcing is another big use here.
Competitive research. Having your VA research these tasks & put together a database of information becomes a 1-day task that has immense value down the road.
Customer Service - haven't done this yet - but having them take messages, be my secretary, handle refunds & answer 80% of the support messages that come in (usually variants of the same problem with a fixed, simple solution).
Basic writing skills (non-native english is tough here, but if you want just a paragraph or so written, they can usually do a pretty good job here - after which I have an native-english editor / copywriter go back through & clean up any leftover artifacts).
True, we decided to outsource, at least partially, lead sourcing for http://codedose.com, as it was just way too much time consuming and steering away from other more strategic tasks, like e.g. "processing" these leads.
I use mine to research all the conferences & trade shows for the upcoming year that I might want to go to. They find out the price to sponsor as well as the price to attend. They even go as far to look for flight and hotel costs.
Also (and I wouldn't have guessed this) but my VA at least is pretty fantastic at handling various social media outlets. Almost zero input from me & she "gets" it. Fantastic.
I don't suppose you'd elaborate on some examples of tasks you give to your VA?