While some people regard mixtapes as the poor-man's version of compilation albums, I think certain mixtapes have their own charm and appeal, especially ones that were personally compiled. The choice of songs, the sequence of the songs' recordings and the "linear" playback nature of the audio cassette tape all provide "personality" to the mixtapes. I used to make lots of mixtapes when I was in my teens till I was through uni/college. Although the initial intention of recording them was for the convinience of not having to change tapes or CDs to listen to my favorite tunes (especially for those roadtrips during the summers of my college/uni years), some of the mixtapes have that certain "emotional association" to it as they accompanied me during certain parts and journeys in my life. Listening to this one that I like to call Roadtrippin' Like It's 1999 for instance, was like opening a time capsule that brought back the "feel" of those times. From the mellow sounds of Dave Matthews Band to the hard crunching stuff by Limp Bizkit and Korn to smooth hiphop/r&b by Tyrese and SWV, it just brings 1999 all back to me. I'm featuring it on Cybersonique!FM right now.

Wikipedia has more on mixtapes.