Is it possible that you are thinking of VuFind? VuFind offers a (fairly basic) set of account screens in addition to offering a discovery layer on top of your OPAC. I'm not sure how well-supported the Unicorn functionality is, but there is a whole mailing list devoted to the subject of interfacing VuFind with Unicorn, so you can probably find out more there.
General information on VuFind:
The VuFind-Unicorn support group:
> -----Original Message-----
> From: Code for Libraries [mailto:[log in to unmask]] On Behalf Of
> Emily Lynema
> Sent: Friday, January 29, 2010 2:50 PM
> To: [log in to unmask]
> Subject: [CODE4LIB] custom interface to SirsiDynix user account
> I have vague dusty memories of someone saying (perhaps at a Code4Lib
> conference) that they had built a custom PHP (?) interface to the user
> account features for SirsiDynix Unicorn. Sirsi provides an API that I
> think could be used to do this, so that doesn't seem like a completely
> impossible thing to remember.
> We have finally 'turned off' our legacy OPAC here at NCSU Libraries
> (after almost 4 years of using Endeca) and would be interested in being
> able to turn off the legacy 'My Account' features as well, in
> if someone had already built an application we could borrow from.
> Thought I'd throw this out to see if anyone else remembers the same
> Emily Lynema
> Associate Department Head
> Information Technology, NCSU Libraries
> [log in to unmask]