
Simplest but least-effective solution: My Vox DA-5 is actually not a bad little amp, on the clean channel. Lately I use it more as a computer speaker than anything else. The .5 watt setting can really be your friend. The effects that it tries to pack onboard are a little dull, to my ears... but the clean channel is really quite nice for such a tiny thing, and I can imagine busking with it. But I often feel a bit cheated when using it.... there are better amps in the room!
I LOVE-LOVE-LOVE my Digitech RP-1000. It might not be quite the thing for a tube or stompbox purist, but I feel I could pipe it into almost anything and find some good tone: a small monitor speaker, PA, headphones, whatever. Usually I send it into my Tech-21 Trademark 60 or Power Engine 60 and keep it turned way down. This device is expensive ($400 lately) but has LOADS of depth and versatility. Running through its hundreds of pedal, amp and cabinet combinations is like going to your filthy rich rockstar friends house. When he's not there to make sure you stay out of his collection!
And now to the reason I'm writing this. I don't have either of these, but damn I wish I did. Put one of these together with a 1x12 or 2x12 cabinet and you could have sonic heaven in an apartment or condo.
http://zvexamps.com/amp_view.html 1/2 watt. Listen to the sound samples.
You can buy them for $499 at a bunch of places, click their dealer links or
http://www.musictoyz.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=M&Product_Code=ZVEXAMP&Category_Code=Zvex+Amps
Unfortunately it doesn't come as a kit, and of course seems more than a bit overpriced. (Editors note: Now that I've researched the issue more throughly it's a completely indefensible price. Stay the hell away from it, but I leave the mention of it here as reference.)
Then there's this thing, the "BAR/OLC Tube Cricket". The kit is only $135 !!! I don't know what the hell it sounds like but it sure is affordable, 1/2 watt. I might just give this thing a try as a first project.
http://www.olcircuits.com/olc_tubecricket.html
Let me know if you buy either of these: I'd be curious to hear about it.

