My Pachypodium lamerei (which I've been thinking was a P. geayi for years, but apparently not) has responded well to the fertilizer this spring. It's retained its leaves longer, and put on more vertical growth, than in previous years. The leaf tips still scorch, which I'm thinking is probably a signal that it's too hot or too dry (?), but aside from that, it looks pretty healthy and happy. I noticed on Friday while watering that it's even growing a new side branch (circled above).
I was slightly shocked when I checked the spreadsheets and found out that I've had this plant for a little over four years now. I got it at Wal-Mart in May 2007 for 53 cents, though it was tagged $3.97. Never did figure out what happened there, but it's probably the best plant-related 53 cents I've ever spent.