mp3 encoding and ID3 tags

iTunes-LAME is a plugin that allows you to use the LAME encoder from within iTunes. It doesn't come with the most recent version of LAME though, so if you were to use that then you would want to download LAME 3.97b2 for Mac from here and install it as well (you just drag and drop the Unix executable right into the iTunes-LAME package contents). If you want a stand-alone app, there is also Max, which can rip to many different formats (MP3, Ogg Vorbis, AAC, FLAC, Apple Lossless) and has the latest version of LAME built-in. It is still in beta.

They both have their advantages and disadvantages. iTunes-LAME doesn't offer any error correction (and can't even use iTunes' built-in error correction), but Max's error correction uses the cdda2wav "paranoia" library which is very slow and, overall, probably not any better than iTunes. Max also doesn't give you any access to LAME's command-line switches--it offers a quality slider instead. Its default setting is "V 2 --vbr-new," though, which is what I use anyway. iTunes-LAME uses only the command line, which would probably make it easier for you to use custom settings.

I personally use iTunes to first rip to Apple Lossless (to take advantage of the error correction, and to archive the lossless files), and then use the iTunes-LAME plugin to convert those to MP3.

What kind of ID3 tag functionality are you looking for that iTunes doesn't provide?