Many open source project have mailing lists a preferred way of communication. If i just sign to the mailing list via my g-mail account i will see ~100 messages per day that are not threaded but just a plain list. What is the preferred way to work with mailing lists so i can see a tree-view of threads and replys?
This is the job of your email client. Each mail sent contains an id, and it is the job of the email clients of the participants to include that id in a header field so your client can recognize it and produce a tree view.
The web interface to gmail is better suited for two person correspondance as it creates a list instead of a threaded view. You may want to use a separate client for threaded lists. Personally I like Thunderbird but your taste may differ.
I usually create a separate folder for each mailing list. Then, if your mail client can show tree of threads, just enable this feature. If you're interested in any particular message - you can create an alert or a filter, that will highlight interested message.
I create a rule to automatically put mail from each list into its own folder.