Overall, I was pleased with the results of my experimentation.
There are two viable languages for browser-game development - Flash and Java. Other contenders, notably ActiveX, are not suitable.
Both Flash and Java allowed me to develop my Snakebite game in about 2 days each - 1 day to learn the language and 1 to write the game. I was able to create browser playable examples right off the bat, though I did have to test and tweak against old versions of Java, and my Flash code is written to version 7, whereas, for compatibility reasons, I would use version 6 going forward.
SDL proved to be a great companion for C/C++, and I was able to rapidly code the game in that environment, as well.
Assuming I go ahead and make more browser-games, either simple ones like Snakebite or more elaborate ones for distribution on gaming portals, I give the slight nod to Flash among the choices. Although it has many drawbacks, including poor performance, it also has the broadest market penetration, and therefore the best and easiest experience for most game players.
However, if I was thinking about something with complex, scrolling graphics, I would do a quick test to see if Flash could sustain an adequate frame rate, and be prepared to fall back to Java.
Neither Flash nor Java seem to be great choices for stand-alone, downloaded games. So I may just choose to write my first full app in C++, using either SDL or the recently released PopCap framework, then port back after the fact. For porting from C++, Java seems slightly more attractive than Flash.
IGDA Web and Downloadable Games White Paper (93 pages, very
Excellent Article on Commercial Flash Development (by former hard-core C game developer)
Evaluating Java for Game Development (lengthy paper by an academic, has some good insights)
SDL Home (Free downloadable SDL library, for cross-platform C/C++ development)