Aimee Mann's appearance as herself on the fourth episode of 'Love Monkey' can't be counted as a connection between the Tom Cavanaugh series and 'The West Wing', on which she sang "Shed A Little Light" in the episode "College Kids". (She was playing a "Rock The Vote" concert, sharing the bill with the Barenaked Ladies.)
This is because those two series are set in different TV dimensions. However, she does connect 'Love Monkey' to 'Buffy The Vampire Slayer' since they are in the same dimension.
Aimee performed at the Bronze, a local club in Sunnydale. (The two songs she performed there were "Pavlov's Bells" and "This Is How It Goes".)
In the episode of 'Love Monkey', she hinted to Tom Farrell that she had mysterious powers, and based on the events in that 'Buffy' episode, she may be right - or at the very least, she's been around them long enough to recognize them.
After yet another vampire ruckus at the Bronze, Aimee Mann muttered, "Man, I hate playing vampire towns."
More than likely that means she's played Cleveland, where another Hellmouth is located.....