A quick look on Version Tracker brings up a lot of shareware. The only freeware I could find was a program called PTHStockTicker, though it supposedly has a portfolio "feature." Might want to check the reviews before downloading.
For your IPhone/IPad you should consider "Stockportfolio" - and you can also access it via Mac using http://www.thestockportfolio.com. Although the prices are delayed, it's really helpful for tracking the performance of your portfolio. It will calculate the performance for a specific period and as it is quick and easy to use, you can quickly open it every day and get an overview of the stocks performance and which to buy/get rid of.