What is the best way to provide feedback to an app's developers and request a feature? Following on from an earlier question that I posed on how to free up space on my Android phone it became clear that a key issue is to request that more developers allow their applications to be moved to the SD card.

What is the best way to let the developers of my favourite apps know of this request?

I considered giving them a low rating in the market and writing in the comment that I would give them 5 stars if they included the "Move to SD card" option. However since I really like the applications and want them to be widely adopted to encourage further development on them I don't really want to turn away potential new users by giving a low rating.
If you want to provide feedback and/or do have a feature request that you want to have answered it would be best to write an eMail provided in the Android Market.
It's located below the description and images of the app.

Also you could check out the website if the developer does have a bugtracker and/or forum (which is often the case).