Tag-friendly mail client

I would like to be able to organize my e-mail with tags. Currently I use Mozilla Thunderbird with IMAP for work and POP3 for home. IMAP is pretty cool. I like how I have the same folders at every computer I go to. However, I seem to be moving on from the hierarchical folder style of organizing stuff into a more tag-based model. I use e-mail to communicate and to organize my thoughts. I know Gmail uses a tag-based system to organize e-mail. However, I don't really like the way tags are handled in Gmail. Because I'm more verbal than visual, I tend to type things out rather than pointing and clicking. I get tired of using the mouse really quickly. This is why I like del.icio.us's method of having the user type in the tags each time. It may be a bit slower but it allows me to organize my thoughts more quickly. And I can type in many tags in one action. In Gmail, it's point, click, select one tag; point, click, select one tag. Finally, Gmail is a mail service, not a client. I'd like a better client to use to check my regular e-mail without having to do the whole Gmail thing (getting ads, being in their database, et cetera). I wonder if the next Thunderbird will support tags. That would be cool.