Here's one I hadn't heard before, reprinted with the kind permission of Project Genesis -- torah.org.
Retold by one R' Becker, who elaborates on it here.
A well-known story is told wherein Rabbi Nosson Tzvi Finkel, (of blessed memory, known affectionately by the Torah world as the "Alter [Lit. elder]" of Slabodka) was diagnosed as having a condition requiring medical treatment at one of the larger medical centers in the area. After listening carefully to the pros and cons of each medical facility, the Alter elected to go to St. Petersburg for treatment. A student escorted the Alter throughout the extended period of his recovery. Upon his return to Slabodka the Alter was approached by a community member who inquired regarding the Alter's absence. The Alter indicated that he had been in St. Petersburg. When asked what occasioned his visit there, the Alter responded that he had gone there to see the push-button umbrella. The astonished student, who had accompanied the Alter throughout the difficult medical ordeal, asked the Alter for an explanation.
The Alter explained that he had, indeed, chosen St. Petersburg after carefully weighing the pros and cons of each facility. However, a short while earlier, the Alter had been traveling on behalf of his yeshiva and had passed through the train depot at St. Petersburg and was intrigued by the sight of the new invention, the push-button umbrella, being opened by a resident of that cosmopolitan city. The Alter, ever vigilant for traces of bias within himself, wondered whether, on some level, his decision to have the procedure done in St. Petersburg was not adulterated by a trace of interest in seeing the novel inventions which premiered there. At the moment that the gentleman asked him why he had traveled to St. Petersburg, the Alter took the opportunity to reflect on his motives rather than to glibly respond with an answer which was too obvious to be useful.