I'm using an Excel spreadsheet in almost exactly the same way as Mneary describes, and it works great for me. (especially since I use Excel at work and it also came on my home PC, so nothing extra to buy or learn
)
The entries can be as elaborate or simple as needed. I find a description column very useful when it comes to both discreet and IC semiconductors. That way I can tell right-a-way if a part I have, would make a good substitution for another part I don't have.
Another VERY USEFUL column is for data sheets. It's very simple to hyperlink them, either saved on the hard drive or from on-line. Anytime a data sheet is needed, it's only a mouse click away!
When I place an on-line order for parts, I copy and paste them into the spreadsheet, and then highlight their cells with another color so I know they're on order.
If you include price/vendor info, it also makes it easy to compare prices with different vendors.
I also have a "wish list" page for stuff I'm looking for.