I have been coming across questions regarding how you can show lists in different sites and subsites when using WSS v3 and i have also asked the question so many times before finding these solutions i would be talking about below.
The Content Query Webpart could have come up to many people's mind if you are using MOSS 2007 but unfortunately not many of us are using MOSS 2007 but WSS v3.
The first and easiest solution is to use the FlexListViewer webpart if you don't need to do alot of customization to the webpart.The webpart was developed by Bart Gunneman.
All you need is to install it to your site collections
add the webpart and point to the list in question.You can read more bly clicking the link above.
The other solution i came across is to use the Content Query Web Part alternative for WSS 3.0
by Eric Kraus. Just click the link and follow his instructions
The last one is to use the old and good Data View Webparts.
I would be posting more on this when i have time and actually show how you could customize a list for multiple sites.
For more tips and trick see Free SharePoint DataView Tips
Enjoy