We run a leading Twitter app (tweetspinner.com), and we are now developing another. This new app, Twêpe (rhymes with crêpe!), can be found at twe.pe (you won't see anything interesting there now, as we are still under development).
Our app is a Twitter e-mail client.
Businesses, of all shapes and sizes. Our goal is to provide a useful service to casual Twitter businesses, or those who don't have time for active Twittering through other clients.
A logo, both light and dark (separate), and also a mark, that can be used as our Twitter avatar icon. The mark could be anything -- we're not sure, and open to suggestions. A whimsical little thing (like bit.ly's fish), or a focus on the circumflex, or something which highlights our Twitter and Email focus... all would work.
Please see the attached palette that we are currently using. We aren't beholden to this palette by any means -- we are primarily developers, after all. Feel free to change it. We do like the orange top bar (remember that the logo and mark must be legible in both large and small), and think that using the orange might be nice for light backgrounds.
Please, no Twitter birds or anything obtusely Twitter-specific.