BuddyCheck
BuddyCheck will show you the real online status of your Yahoo! Messenger friends. It will regularly check to see if they are online, even if they are invisible or are using Stealth Mode. It will notify you using a tray area balloon when a contact signs on or off. ... Messenger account that you have. ... You can customize the period after which each contact is checked again for change, and you can set individual checking periods for some of your contacts. ... You can also easily import contacts from any Yahoo!
http://www.nuotex.com/buddycheck/files/BuddyCheck-Setup.exe - 327Kb - Download - Screenshot

ProductiveMail
ProductiveMail lets you know in real time when your emails are received and read. Its main benefits are: - Make sure that your outgoing emails were received and not blocked as spam. - Real time notifications when an email you sent is read for the first time. ... - It informs you at all times the status of your messages: the date and time they were sent, the date and time they were read and the time elapsed between both events. ... - You can hide the message footer to make the read receipt completely invisible.
http://www.productivemail.com/en/trial/productivemail_en_102.exe - 2Mb - Download - Screenshot