It's always best to sample the wares before you plunge into something, like eating the bite-sized food on trays at Price Club, or sleeping with your wife before accepting 40 cows to take her off her father's hands. Get a taste of bands before you plop down cash for their tickets, at Bits and Watts.
The brainchild of three local music aficionados tired of wading through countless media to keep tabs on local shows, and sometimes not even knowing what the bands sounded like, B&W's a free service that aggregates deets about upcoming gigs at smaller venues throughout Philly, then gives you a sneak peek of the artists slated to perform via streaming audio, which will make you wet your desk chair if you listen to it long enough. Simply choose a specific date/date range (up to 12 weeks from current date) or one of 18 venues, and B&W'll return a calendar-based list of every show, complete with links to the venue's homepage, official band sites, ticket purchase options/info, and event specifics like set/door time and opening acts, so you can make sure to miss them. But what really sets B&W apart is the aforementioned streaming audio: all bands returned in a search get coupled with MP3s sourced from music blogs around the 'Netz (complete w/ track skip controls), and additionally, a widget on the calendar page'll play a rotating selection of tracks from bands scheduled to perform over the next three months, filterable by venue or genre, at which point you'll be completely crushed to learn Rap/Rock no longer exists.
B&W encourages bands and venues to provide/update info and audio tracks as often as they like, and they also maintain a blog that's updated several times per week with gig previews and detailed descriptions of featured artists, often including links to ticket giveaways -- helpful, because you'll end up completely broke if you're paying for you, your woman, and your livestock.