Trillian, the IM Swiss Army knife from Cerulean Studios, just updated and every premium feature (except for cloud-based logging) is free.
Trillian will still rock a Free/Pro arrangement but the Free side of things just got a whole lot more awesome. All the great but previously premium features like themes, activity history viewer (a super charged chat log viewer that includes bookmarking), and multi-location sign-in with seamless switching between chat clients (no more messages getting lost when you move between your phone and desktop, for example). Right now the shift-to-free only affects the Windows edition but the Mac and mobile editions will receive the same feature shift in their next update rotation.
The premium version has shifted to a subscription model. For $12 a year you get the same feature bundle with no advertisements and cloud-based chat log storage and syncing. You can read more on the Trillian blog here or hit up the link below to download a copy.