Not fully researched yet, but to get you started:

Guided tours of Brentford, Sundays in summer, 2.30pm approx outside 'Goddards' furniture shop.

Waterman's Arts Centre - film, theatre, music, gallery. What more could you ask? On the Hight St, opposite the end of Ealing Road.

Musical Museum - music boxes, player pianos, that sort of thing - some organ recitals, too. High St, towards Kew Bridge. Open summer weekends.

River Ferry - from other side of Kew Bridge ('Kew Pier'), to Westminster or Hampton Court - summers only.

The Thames - offers good walks in either direction. Heading east, you can walk along the north side, past the old riverside houses (and pubs) of Strand on the Green and Chiswick Mall, not to mention the Fuller's Brewery. On the south bank you'll have a greener time of it, passing Mortlake, Barnes and eventually Putney. West, the south bank takes you around Kew Gardens (with Syon Park on the other side, you really feel away from the city) down to Richmond, That's a nice bike ride too, making Kingston & Hampton Court within easy reach. Chase up the guide book for the Thames Path, covering the Thames Barrier to the source of the Thames.

Syon House & grounds - open all year round. Also includes a garden centre, gift shop, gallery. Pedestrian access from London Road (other side of canal bridge), cars follow signs through Isleworth.

Boston Manor House & Park - a house with a chequered past, and a rather charming park, despite being literally underneath the M4... find the little paths down to the river.

Gunnersbury Park - on the other side of the A4, slightly towards Chiswick. A huge, and often more or less empty, park. There's various exhibitions in Gunnersbury House towards the north side (Popes Lane in Ealing), and pitch & putt, a small toy boat lake and lots of trees.

Osterley Park - a mixture of park and farmland, around Osterley House. Not technically in Brentford, but close enough. Occupies the area between the canal to the north of the A4 and Southall. Access from Syon Lane. Intersected by the M4 motorway; in fact you'll recognise it as the last decent piece of greenery you'll see from the motorway before you get on the overpass and enter the urban hell that is London...