Textmate is another excellent example. Search in project is completely usable with an SSD. I had temporarily switched to AckMate because of how unbearably this feature was, now it's instant again.
Booting faster is the least of my cares as my laptop is only rebooted when updates force me to.
A fast CPU is worthless if you're burning 30% of your cycles waiting for the HDD to deliver your data. Relying on file cache is not good enough.
Just to give a rough idea - 4k random writes:
Vertex 3 - 214 MB/s
WD VelociRaptor - 1.9 MB/s
$200 for an SSD is a far better use of money for the average programmer than say the upgrade from I5 to I7 on a 13" MBP. There are many parts of your computer which you'd spend $200 on that get you less of a general every day performance boost than a SSD.
The reality is that it significantly increases performances for all workloads but streaming videos (huge sequential reads).
Most of computer usage is random access to small files, and that's a field where SSDs utterly annihilate rotating platters (not that rotas have any advantage but storage capacity, mind you, SSDs are also superior in seq read and write, but on random we're talking 2MB/s on 4k random write for a VelociRaptor to >200MB/s for a Vertex 3; 0.68MB 4k random read for a VR to >90MB for a Vertex 3, for sequential performances the difference will be a factor of 2 or 3 tops between a VR and a top-of-the-line SSD)
The difference is, of course, even more impressive for laptop drives: most laptops don't house 10k, 10W monsters like the VRs
Those of us with one know that really isn't the case, but of course it's hard to convince someone to spend that much money on something they don't think will make a difference.
Since I put one in my late-2008 MBP at Christmas, I've not seen a single beach ball. Best upgrade ever.
Either that, or a case of blub.
SSDs are one of those pieces of hardware closest to magic you can find, the differences between HDD and (modern) SSD are so big it's hard to understand them until you've experienced them. I know I didn't before I got mine, but Anand's writing on the subject convinced me there was something to it (anand being a person whose opinion I respect greatly, and one of those who dived early into understanding SSDs, he didn't hesitate crucifying early crappy SSD, and his SSD series are fantastic in their breadth and depth)
Then the Crucial RealSSD C300 (256 GB) went on sale prior to xmas 2010, and my girlfriend ordered one for me surreptitiously, after overhearing conversations between me and a friend about SSD performance.
As it turns out, I was completely wrong to be skeptical. The differences should have been crystal clear to me. Think of the difference between using your iPhone/iPad/Android and your computer. Notice how everything on your phone occurs nearly instantly. Most of us don't even consider it, because these devices never came with slow magnetic platter drives. Even with minimal (by desktop standards) RAM and absolutely anemic CPU power, these devices manage a level of responsiveness that makes them disappear in to the background as we use the software. An SSD brings this experience to your desktop. The performance difference is present in everything that you do, not just launching applications.
What a horrible argument.