Arto Vaarala has realease a vst arpeggiator named Kirnu. Kirnu has plenty of features such as: Easy realtime tweaking, User friendly pattern view, MIDI learn for every major control, Two independent CC controls with 'teach' functionality, Numerous of different scales, Hold mode and more.
The best part about Kirnu is that it's totally free! Actually Kirnu is a donationware plugin and be sure you send Arto some green ones if you really like and end up using Kirnu. Head over to Arto's place and download the plugin. Available formats are: VST/Win32, VST/Win32nonSSE2, VST/Win64 and VST/MacOSX32.
Now you wonder why I post this at my blog?
Yes you're right, I did help Arto with the GUI for this plugin.