Something to keep in mind with budget SSDs, which may be what Hellhammer was getting at, is that the MacOS as of 10.6 doesn't support TRIM. In an SSD with good garbage collection, this isn't an issue, but in the case of a very cheap one that doesn't do good garbage collection, it could lead to a drastic decrease in performance over time as you create and delete a lot of files.
I'm pretty sure than any SSD that uses a SandForce controller (which tend to be higher-end) is good on that count, and others may be as well, but it'd be worth checking into.
That's one of the reasons it's worth it to many--myself included--to pay the premium for OWC's SSDs--in addition to a SandForce controller, they seem to have custom firmware that maintains speed extremely well over time on the MacOS. It's possible that other SandForce drives will perform just as well, but I haven't seen any specific tests to that end, and here's one detailed test that demonstrates the substantial performance hit involved with poor garbage collection:
http://macperformanceguide.com/SSD-RealWorld-Compare-fill-volume.html
I just put an OWC SSD in my new MBP, and it's impressively fast.
If you don't use CDs/DVDs much, another option for your rotating hard drive is to replace the optical drive with it--that's what I did. This will involve buying a caddy for it (which can be relatively spendy to get one that'll fit in a 9.5mm bay), and maybe also buying either a portable external optical drive or a case for the one you pull, but it's worth the trade-off to me.