I have now implemented the request feature, compiled a client binary for win 7 64 bit, and e-mailed it to seth. I talked with him on irc earlier on. Later I might submit this as a patch to the official client if anyone is interested. It wasn't a big job at all, when I first got to coding, but setting up the entire environment for compiling took a long time.
As it is now, it checks for "0/unconfirmed", and once that message pops up in the client, the client will play a sound of your choice. Currently this is just a file named test.wav in your directory. I have just tested it on my win 7 64 bit system, and the only files altered are the ui.cpp and the makefile.
Not sure if more people are interested, then let me know, and I may put out the source. I will at some point anyhow, but I tought I'd refine it a bit more, even if it works now.
There is a glitch tough, the send coin menu item and the adress book item seems to no longer behave perfectly graphically speaking, sometimes when moving the client around the screen, or resizing it, the graphic in the menu line is affected and looks a bit odd, I don't know why this is, but will research it later on.
Complete source is available for the topic starter, and also instructions for how to set up the environment for compiling were sent to him, although I must frankly say that these procedures are a bit daunting for a non-programmer.
Let me know what you all think, and I will check in on this thread later. And please do not complain that I have not put up a binary and/or source yet. I will, just waiting for feedback from the topic starter.
The libraries I have used are windows specific, so this solution will most likely not work for any other OS at this point.
If the only activity you have in your wallet is from mining, then this is acceptable, however, if someone sends you an arbitrary transaction, it may give you a false positive..