Wow Web Stats (WWS, Wow Web Stats) is still regarded quite highly. However, it does have a number of shortfalls - the two biggies, off the top of my head, are that a) numerous Ulduar fights are not being correctly parsed, and b) pets are not counted towards their owner's damage.
World of Logs (WoL, World of Logs - Real Time Raid Analysis) is a relative newcomer, and we are very much liking its results. Instant log parsing/uploading (live sessions) is its claim to fame, but it does pretty much everything the others do.
As per addons, the only one I have related to combat logs is LoggerHead, which automatically will activate log recording upon entering user-defined zones, and will automatically turn off logging upon exiting these specific areas.
For other a combat log splitter, I use WoW Combat Log Splitter (wowclsp, wowclsp - Google Code) to break down my rather large files into the individual raid nights. This is an awesome tool, and I recommend it highly.
Fuster's Log Splitter (Fuster's Log Splitter - Home) is another option that I toyed around with a while ago, but am personally sticking with wowclsp.
Each of the first three links has their own applet to upload/parse/archive/whatever to the data. A really cool option in WMO's uploader, in the second tab, is a place to merge multiple logs. This can be invaluable in getting one good log for those sites that do not handle the merging of logs on their end.
There are certainly more resources than the ones I mentioned, but this seems to be a pretty thorough overview of the general market, even if it may not be all-inclusive. Definitely play around with each of the utilities and sites, as there are cool little goodies to be had in each program.
Is there a parsing program available that can export the information to a spreadsheet?
In the case of Microsoft Excel, the included tools are sufficient for this purpose, but require several stages of formatting.
From Excel, open the log file, be sure to have the file viewer set to look at all files (*.*). You will immediately get the Text Import Wizard. Select the "Fixed Width" radio button, then hit Next for the rest of the steps.
You'll need to bring up Text-To-Columns wizard to complete the import. In all "modern" versions of Excel, you'll find it in the Data menu. It's similar to the Text Import Wizard, select the Delimited Option this time, and in the next step, select Comma as your delimiter.
Other spreadsheet programs should have similar tools and processes to the one I described for Excel.