Question: I have a website in Sharepoint 2007. We use a wsp to deploy our projects. We can deploy dlls, usercontrols, features, but i don't know how to include new lines in the web.config.

Which would be a possible way to make changes in web.config?

Another thing, how can I include resources (resx) in the wsp?

Answer: 
In addition, if you think about using appSettings from web.config for your site configuration values, you actually have other options as well. For various reasons web.config might not always be the best place to put your values - at least not if a "superuser", etc. is supposed to be able to change them later on. For this, you could instead use a Config Store-feature, which also scales across the farm for multiple front-end servers, etc.:

<http://www.sharepointnutsandbolts.com/2008/05/introducing-sharepoint-config-store-for.html>
I think direct web.config manipulation can get tricky when you have multiple servers. If your entire installation is only on a few servers, it just might be easier doing that than trying to make simple web.config changes via code.

Plus, manipulating the web.config directly ensures you have a complete web.config in your source control system. If you use the API to make changes, all you'll have in source control is a bunch of C# code that you hope are bug free!