I'm tempted to write one myself, but I've got a lot of other things on my TODO list right now. Here's what I'm imagining:
+ Open up the index.html page that is the GUI and you'd be asked for the host:port (default: localhost:8332), username and password.
+ And it'd show your default receiving address, have a Send Bitcoins button, etc.
+ And it'd poll bitcoin/bitcoind every, oh, minute or so to look for new transactions.
We are developing something pretty close to this based on a stripped down copay wallet. It is self-contained JS/HTML with no external website dependencies and it is can be setup to use only the bitcoind rpc. It is designed for use with the iguana chrome app which will be a oneclick install that gets the JS GUI along with pnacl pexe that implements the bitcoind rpc, among other things
My feeling is that having something that can be run with a oneclick install will reduce the adoption barrier among the non-technical population. I know a lot of people wont want to touch a chrome app with a 10 foot pole, but the codebase is portable C, so there are also native versions.
Regardless of whether the chrome app version or native version is run, or whether the iguana is run at all, the same JS/HTML would work. I would be happy to have a version specific to what you want made so you wont have to worry about including iguana and the 50,000 lines of C code that is compiled into JS bytecodes.