ystockquote is a Vala library which exposes APIs to get Stock data from Yahoo (finance.yahoo.com).

http://greenido.wordpress.com/2009/12/22/yahoo-finance-hidden-api/ has a good reference of tags.
http://code.google.com/p/yahoo-finance-managed/wiki/YahooFinanceAPIs provides lot more info on Yahoo Finance API.

BUILD:
run build.sh to build sample executable.
run build_lib.sh to build shared library from the Vala code.

USAGE:
run "ystock_sample <symbol>" to get the stock data of the symbol.