FUNWITHSTUFF  The secondlife.com website, for some time up to and including December, did not allow you to see which friends were online, making this widget fail. The website is again functional, though this widget required an update due to a change in their site. Until I manage to update this listing, please grab the updated Second Life Friends Online widget v2.2 from http://secondlife.funwithstuff.com.  
(Version 2.1)

FUNWITHSTUFF  Just to be clear, you don't need a credit card and it's not a "trial". Second Life is free, unless you want money to spend in-world. Universal binaries run well on the latest Intel Macs, though it's still under development and there are a couple of crashing bugs. Worth a look.  
(Version 1.12.1.13)

FUNWITHSTUFF  Well, I should read more closely before posting; there's a solution hidden in the read me, but it's less than ideal. It suggests using a specifically named alias to point to the library you want to use, but that's no good if one of your libraries has that name already and you want to see another one. Why not just look at the library iPhoto is currently pointed at?  
(Version 2.5)

FUNWITHSTUFF  Doesn't seem to recognise an iPhoto library if it's not called "iPhoto Library" and sitting in your Pictures folder. It's very possible to use multiple iPhoto libraries and to call them whatever you want (hold option when starting iPhoto) so this makes the product a bit useless for me. iTunes support seems to work fine; I'll contact the developer.  
(Version 2.5)