Dashquit
Dashquit is a small widget for the Dashboard. It will quit the Dashboard and thereby freeing ram for to the system. The widget also displays the amount of ram used by the Dashboard.
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Adium
Adium is the ultimate Instant Messaging client supporting MSN, GoogleTalk, ICQ, AOL and a lot more. Additionally numerous user made themes, plugins and more.
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UNO
UNO unifies the theme of all windows making the look and feel clean and "delicious".
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LiteSwitch
Simple keyboard switcher - mmm - veeery nice
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Coda
If you are webdeveloper and uses php, this is the editor for you. Includes site management, editor, style editor, ftp tool, update management and even books.
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Transmit
A nice no nonsense ftp client
iTerm
Console tool - the cooler way
Synk
Synk is a nice backup tool. It comes in three versions depending on the needs.