
If you need to send multiple attachments to an email, you should check out Attaché, an AppleScript droplet by Martin Michel. This add-in quickly creates an new email with all the attachments included and listed. You can put Attaché anywhere you like, though the Desktop and Dock seem the most logical locations, and then simply select the files you want to send and drop them onto it. Best of all, Attaché is free and can be downloaded by clicking here.
Source: "Attaché: Droplet for Quick Mail.app Attachment Lists" by Tim Gaden, published at his excellent Hawk Wings blog.