Microphone into Arduino

Hello,

Am i able to connect a microphone (e.g. sm57) directly into the arduino? and if so, how would i go about amplifying the microhpone signal. I want to avoid using the mini sound sensor microphone.

No, use the sound sensor.

SM57 will put out ~+/- 1V signal. You will need to give it a gain of 2 for +/- 2V signal and offset the level to 2.5V so the analog input will see 2.5V +/- 2V, or a 0.5V to 4.5V signal.
You can do that with a non-inverting summing amplifier.
http://masteringelectronicsdesign.com/the-transfer-function-of-the-summing-amplifier-with-n-input-signals/
Set up Rf1 and Rf2 for a gain of 2, V1 will be the mic input, V2 will be the offset voltage of 1.25V (x2 = 2.5V).
Use a good rail-to-rail single supply op amp.
For example, pick one here where the upper supply can be 5V:
http://www.digikey.com/product-search/en?FV=fff40027%2Cfff800dd%2Ca40070%2C1140050&k=op+amp&mnonly=0&newproducts=0&ColumnSort=1000011&page=1&stock=1&pbfree=0&rohs=0&quantity=&ptm=0&fid=0&pageSize=25
Sorting by price, the MCP601 looks like it would have plenty of performance for buffering audio signals, and is probably overkill for sampling with the onboard ADC that can only sample at ~ 10 KHz rate for 10 bits.

CrossRoads:
SM57 will put out ~+/- 1V signal.

You can get-out about 1V if you stick it next to jet engine!!! Normally, you need a preamp. The [u]Shure datasheet[/u] says 1.85mV @ 94dBSPL.

You can probably get a usable signal without amplification if you stick it in front of a kick drum or in front of a cranked-up Marshall stack. But, you still need the offset/bias.

Ok, so maybe an additional gain stage or two to get up to line level outputs.

I never looked at the output level of mine where they went into my 8-channel mixer.

Is it possible to introduce a c weighting filter so the microphone then acts as a (poor) SPL meter?

Technically, anything is possible. Do the filtering in software after digitizing, do it in hardware before digitizing.